Yes, but it really doesn't sound appropriate for any of the unimplemented spheres.
It would definitely fit best in the Law sphere. I've been giving Host of the Einherjar the Guardian promotion for a while. Being more likely to defend synergizes well with getting +1 duration per kill.
The only other summon I can think of that should have Guardian is the Guardian Vines. It hasn't been a summon in a while (it just recently returned to the game only for use in scenarios, although its 'pedia entry does make it sound like it is still a Nature summon) but I plan to bring it back as the Nature III permanent summon and give it some poison damage and the Entangle spell too. Vitalize fits better in the Creation sphere.
I also make Aureales see invisible units, have a bonus vs recon, and the ability to target recon units in stacks of stronger units so they are really good at killing assassins before they get close enough to hurt you.
I personally think that FF's Dimensional sphere spells (including one pseudo-spell that is really just airdropping permitted by promotion) are quite good and should be adopted in FfH. I may want to see if I can get a Dimensional 3 spell using the portals from The Cult to work before borrowing them myself though. This would allow moving an unlimited number of units back and forth from two remote points on the map each turn, so a single archmage could allow hundreds of units to appear within striking distance of any enemy city. I think it would be pretty easy to do if you the spell created a portal on the caster's tile and linked it to one created in the caster's owner's capital city. There would mean that you could only have 1 pair or connected portals per player at a time, unless perhaps you move your capital. I could probably set it up either so that making a new portal destroys the old one or so that having one already blocks making a new one until the old one is destroyed. I'm trying to decide whether having hostile units enter the portal's tile should destroy the tile or if you should be able to steal a rival's capital city if you manage to slip a unit though their portal. I think I may be leaning towards the latter, as such a powerful spell deserves some risk. Creating a portal from your capital to a rival's shouldn't just allow you to attack without reprisal.
I also think that each level of Dimensional should provide some boost to a summoner's summons.
I'm not a fan of Vehem's Force I spell (Accelerate, a version of haste for mechanized units) at all, but I really like his Force 3 spell. (I liked his 0.42 Force spells better.) I'm ok with the ranged attacks that level 2 allows, but I like it better if each level provided a smaller ranged attack that added up. I still think that one spell should represent the Balance of the sphere. I'm thinking my version of Force I would be Moderation or Temperance, a spell granting units in the stack a similarly named promotion that gives resistance to both Holy and Unholy damage, to protect the agnostics from both heaven and hell alike. I also feel like having a scattering spell available to non-dragons could be cool, but now that Roar can scatter units out of cities it might be too strong. If I did make this a force spell I'd make it level 3 and make a weaker Wall of Force a level 2 spell.
I'm not really a fan of FF's Creation spells. Growth is ok I guess, but I do not like his Fertility. Changing one resource to another doesn't really fit the sphere imho. Creating a new resource might, but that would probably be too strong. Birth can be nice, but not that useful in the late game due to its population cap. It might be a good spell if the cap were removed but it only worked in a city that had enough food to slowly grow anyway, and then possibly moved down a level. As stated earlier, I think that Vitalize (Nature III) fits perfectly in the Creation sphere (probably at level 2). Actually, Inspiration (Mind I) might fit well in Creation too, as sphere represents fertility of the mind as well as body. Amathaon is the ultimate Genius, in the modern too but mostly ancient sens of the word.