Now to poke some holes in your overarching fact deficient very base list.
1. Base str from 5-8 is basically irrelevant. It's the Promotions that make the difference No one attacks with a Non promoted unit.
2, Axe (copper) is str 7. Obsidian 5.
3. A str 6 Javelineer is bane to most units Including the Arsonist.
4. Composite bow are not main offensive units. But set them on a forested hill and it's like they are in a well built and supported castle. Again promotions. But they can handle arsonists too.
5. Light sword is Not in this timeframe until late. so not that relevant a comparison. Obsidian sword at 6 is your 1st sword unit and very effective against arsonists. Of course you have to get obsidian but they are in the same timeframe.
6. Where are the mounted units? They too can be very effective against Arsonist.
7. Arsonist receive the least amount of Promotions of every unit listed so far.
8. Mace is a seldom main unit for attacking another unit Except when they are 1st introduced into game play as Stone mace (Preh Era). Otherwise metal (Copper) is a support unit.
9. Hand rams are a joke.
10. Rams are wasted production as fodder units to die upon the walls of a city. And have no real value because of this narrow role. But yet you would like to force everyone to use them.
11. Battering rams are better but come later about the time the 1st catapult or ballista units start to show up, basically late in this timeframe.
1) Strength is far from irrelevant as it forms the very basest expectation of victory. Natural modifiers are second most important (including things like withdrawal). How many XP you can get into them (you're calling this how many promotions they get) is a potential factor depending on a few things.
2) I didn't evaluate axes in this because swords are supposed to be stronger by a point than axes so I assumed they were at 6. If they have been increased to 7 then swords should be increased to 8. (Maces should be the same as Axes and have been dramatically left behind during this era in terms of adjustments.) Axes are an anti-melee unit and are given +25% vs Melee, so they really weren't a unit to put in direct comparison to Arsonists. They can be a good city defender and field fighter to help defend stacks against other melee units and try to take advantage of swords (since the +25% puts them as stronger than the sword when they clash, despite the swords higher overall strength). But they are inert in terms of natural modifers against arsonists (throwing units), and thus are just a base strength to strength comparison there. With arsonists at str 8, the Axe is unlikely to fare well against the Arsonist, being a point weaker. An extra promotion MAY be worth +1 str IF you are playing with SM, but usually a promotion itself is worth a bit less than that if you aren't. The standard is +10% combat modifier for a promotion. So if an Axe is getting an extra promotion over the Arsonist due to more buildings giving melee XP bonuses, then without SM, you can increase the value of the Axe str by an average of 10-15% str depending on how applicable the promotion it takes actually is in the fight. The arsonist is still a little better than the axe in this evaluation. Both on defense and offense, and far better when you consider the special abilities of the arsonist, which may apply against the axe as well. More on that below.
3) The Javelineer, like all throwing units, has a natural bonus against archery units and has some withdrawal ability. It adds early withdrawal ability if applicable as well. Like other throwing units, it has a very light amount of collateral when it attacks due to the weapons fanning out and striking other targets during use. It doesn't have any natural bonus against other throwing units so against an arsonist, aside from the withdrawal and collateral they both share as throwing units, they would be fighting each other as equal units. They get the same amount of promotions because they are both throwing units, which is what is giving them a diminished amount of promotions in comparison to melee units which get a lot more bonus sources among buildings defined. The Javelineer upgrades in the late Classical to a Skirmisher which has 8 str. Therefore, the Arsonist is already at the upgraded strength level of the Javelineer and in all other ways they are completely equal except that the Arsonist has 8 strength while the Javelineer has 6 and they are timeline concurrent units. Clearly the Arsonist is the FAR more powerful unit than the Javelineer (the Javelineer may have a touch higher withdrawal and the Arsonist a little higher collateral if I recall correctly.)
4)I wasn't putting the Composite Bow in the mix as a comparison regarding offensive units but as the main unit that Arsonists are there to fight. Composite Bowmen are the primary city defensive unit and although they do have a strong city defense %, probably higher than the Arsonist's city attack% bonus, the Composite Bowmen are a strength 5 unit trying to hold off a strength 8 unit. At the base, the Arsonist is already starting at more than 50% stronger, unless the right buildings are in place. This is really skewing towards making cities far easier to capture than to try to defend.
5)The Light Sword IS late in this timeframe which aggravates this balance scheme even further. Being a swordsman unit, it is intended as the most core city attack unit and yet it is outclassed and outgunned by the arsonist which has been in play for nearly an era already by this time. They share about the same amount of city attack% bonus but the light sword is weaker by strength, does not have any withdrawal, does not cause collateral, and does not have any ability to bombard. Yet it's supposed to be a major step up in the strength you can present when attacking cities. It is failing to provide this in light of the dramatic overpowering of the arsonist.
6)Mounted units are strong at attacking throwing units yes. Of course you MAY or may not have access to some. Their strength is equivalent, about 7 or 8 depending, at this stage, and with their natural combat % bonus against throwing are very likely to kill unprotected arsonists. This makes arsonists vulnerable to them in the field. However, only some more advanced mounted get the ability to gain any defense bonuses and even then a lot don't. Therefore they cannot get any benefit from defense on the tile or from abilities when trying to hold a city, and with the city attack bonuses granted to the arsonist, they are also likely to fail to defend a city from an arsonist's attack. It's also pretty easy to throw a few spear units into the stack with your arsonists to defend agains their assaults in the field so it's not hard to get the arsonists up to the city even if your opponent does have mounted units.
7)Arsonists get fewer promos because they are throwing units. That can not only change by building designs at any time but it can also easily be drowned out by placing military trainers in your cities that train them. They can easily gain a lot of promos if you try. They are combatants and benefit from any XP source that applies to all combatants, which CAN be the majority of your XP sourcing despite buildings depending on how the game goes and how you play it. Furthermore, aside from mounted units, throwing units have few vulnerabilities. There are no melee units (which get the lion's share of added XP benefits from buildings) that have a natural counteractive combat bonus against throwing like axes get against other melee units and spears get against mounted. Axes make most melee units very vulnerable and very counterable. There is NO defensive unit that gets a natural anti-throwing unit benefit, which is part of why Javelineers are great to use on the attack, but Arsonists are outright better. This means stacks are hard to protect against throwing units unless you have some units in there that specialize in anti-throwing promotions and the AI doesn't yet realize they need this as much as they do. Therefore, not only are arsonists lethal when attacking cities, they are also great at breaking up stacks because primary stack defenders are very unlikely to be strong enough to stop them from not only surviving and killing the lead defender in the stack, but also causing collateral in the process, thereby damaging the next best defenders and making it easy for follow up attackers to wipe out the rest of what you've encountered on a plot in the field.
8)So we agree that Macemen have basically been forgotten as a useful unit by this time by being left behind in the strength ratings and their awkward anti-melee/city attack blend doesn't help much against archery units (though CAN be better against axemen if that's all that's left guarding a city.) They need beefing.
9)Hand rams are a Prehistoric era unit that is really only for those first conflicts and precede arsonists usually anyhow. Usually once arsonists are in play, you have better rams either right around the corner or already.
10)Yes - Rams should be the main way you have to take down the walls at this point and they are meant to be costly. Another step that has not quite been completed in this scheme is to make Siege Towers (later developments anyhow) capable of enabling a limited number of units to attack without reducing the defenses to the minimum required level to attack, allowing swords and javelins to break apart the immediately strongest threats harming the rams before the rams head in. Still, I don't mind if arsonists do a little bombardment, but they shouldn't be doing more than a few % in a round, just enough to take a little of the edge off and give your rams a better fighting chance.
Please elucidate on these "many non-strength abilities the arsonist has".
Withdrawal, collateral, bombardment, city attack%
All of the abilities that mounted, other throwing, and dedicated city attack units like swords and maces have combined. PLUS the unique ability to bombard the city defenses without threat to themselves. As throwing they are also hard to counter and get a natural anti-archery bonus.
Look I know you will change them. You can't help yourself. Because you are driven to follow your overall design scheme. I understand this fully. So I buck at you at times on small things like this (And when necessary on large things), just so the player that is not like you can have something to play with.from this Great Mod started by StrategyOnly. And SO has handed you the keys to the car. All I can do is back seat drive.
Oh and can you turn the A/C up a bit? And you went thru that last light on the yellow and it turned red when you were in the middle of the intersection! Did no one teach you about stale Green lights a block ahead? And it's a block closer and 1 less stop light to the grocery store if you had turned right at that last corner. Are we there yet? Oh and the floor is covered in soft drink bottles! Don't you ever clean this thing out? Is that gum on this seat!??
I'd prefer it if you could understand that the 'why' involved in this is not
just a personal opinion but based on design plans that extend from original Civ IV vanilla to extended game concepts that others began and I agreed with and wished to extend out, as well as yes, some personal design concepts regarding throwing units and where they fit into the scheme in general. If you could see the light on the why of this whole design setup, I think you might appreciate it more.
Thank you for keeping this conversation civil though. It means a lot.