I could see mithril phalanx, and mithril vampire ... getting possibly out of hand?
But then, maybe its worth a try ^_^
( after all, without the base strength increase .... the other promotions won't be as 'effective' per se .... so maybe its more balanced on all accounts?

)
I makes mithril phalanx obscene (24

).. although i've never even seen a phalanx in a PvP game so I don't know what to make of that. You'd probably have to reduce phalanx and beserker

by 2.
It actually weakens vamps. assuming a mithril vamp fed up to combat 5 (very reasonable), you are getting total

of 18 instead of 20.
As much as I like the idea of % bonuses, it's probably too big a change for too little a return though

.
Edit:
I don't really think that melee perform 'poorly' ....
on the other hand, with this change, you could argue that ALL melee units could get ALL weapon types, due to the scale

Mithril Warriors!!!! Sounds fun
I hadn't really considered that, but I guess it could work
In terms of melee function: they aren't as bad as archers, but the 1

makes them subpar because they really need mobility 1 to be functional (requiring you to dip into horseback riding anyway, which is an opportunity cost. May as well go horses). I can't speak for EitB changes because we've been playing EMM pretty casually so far, but certainly in vanilla where I played PvP more regularly PB hunter or HA spam was the go-to outside of UU dependent strats. A hunter with combat 1 and shock beats an axeman with bronze, mobility and combat 1 (6.4 vs 6) for less

and identical

. With only mobility vs combat 1 the axeman beats the hunter at 4.8 vs 5, which is very comparable, until you consider the

difference (425 vs 1350 in vanilla). Of course, you can ignore mobility to make that 425 vs 725

and retain superior combat odds.... but 1

is *very* limiting, especially on defense.
PB vs Iron favours the hunter even more (8 vs 7.2). PB Rangers vs Iron Champions is brutal (12.8 vs 9.6) even with Enchanted blade (12.8 vs 11.2).
Actually, re-reading my analysis, I think the problem there has more to do with the lack of anti-recon promo and mobility 1 placement in the tech tree favouring those two lines. If you changed those two things suddenly melee is quite attractive.....
Double Edit:
Honestly I think that adding +20% city attack to Champions (and *some* UUs such as Battlemaster and Boarding Party) would be best
You're right, something like that would be simpler. I've gotten carried away with big ideas

. I don't think it's quite enough to solve the issue of axemen being more cost effective than champions, though. 2 Iron Axemen still breaks even with 1 Iron Champ in cities and beats them in the field or on defence for identical

(let alone for 30 less). How about 1 free promo for Champs as Calvente suggested? Fits the fluff and makes them a lot better vs axemen. Also, that makes PB Ranger vs enchanted blade Iron Champs 12.8 vs 12.8!
Mimic gimmicks aside, some of the Champ UUs (Boarding party and mimic) are so bad axemen out-perform them :-(. It's a bit sad when your UU *discourages* you from choosing its tech path. They really need 6

That's a separate issue though I guess, and lanun especially don't need buffs.....