[Agema]

QM's pretty much right: mostly they need to make sense thematically.

I can't fault his mage suggestions. Bear in mind some heroes can supply enormous advantanges - for instance Tjatse in Utgard/Jotunheim, who is not only a genuine SC but even can have A4, when without him the nations have no natural Air magic at all. But heroes that powerful should be rare, and his suggestion of just a modest boost over natural national capabilities is a good idea.

I would flag up just one issue on fighter heroes, though. 15 Att/Def is supposed to be utterly exceptional, the absolute limit of human capability. Even fighter-build pretender gods tend to be in the range of 12-14Att/Def. So if you take a base human unit or commander and make a hero version, you should consider 14-15 exceptional, and more than 15 a no-go. Consequently a bonus of 2-3 Att/Def might be more realistic: a hero based on a knight might have 14-15Att/Def, a hero based on an ordinary heavy infantryman maybe only 12-14. If you're modding units already superhuman like Van, maybe there consider going over 15, and even then maybe consider giving them extra special abilities instead. Special abilities are often a good way to go - reinvigoration, stealth, recuperation, resistances, sacred and so on.

I have quite a low opinion of many fighter heroes - many of them won't even make adequate thugs, at best they're units to chuck a cheap magic weapon or (say) fear item onto, so you mix them in with normal troops to add a bit more oomph. Whether you want to make some of them thugs, even SCs, or leave them sub-thug is up to you.