For comparison, the other exotic d10 weapons are katana and bastard sword. Both of them can be affected by either 1h edged or 2h feats. Warmace does not have this treatment, truthfully for reasons I am unsure of.
I would suggest opening warmace to also be affected by 2h feats. Those who go 2h would gain a tiny bit more versatility for 1h and shield weapons as shields become more prominent, as currently the katana and bastard sword are limited only to lawful in the case of the former and human barbarian in the case of the latter. Meanwhile warmace has good only and evil only, which would dramatically increase options for people who go exotic and 2h feats who find themselves non-lawful and not a human barbarian and without UMD. A small benefit too of this is half giant ranger, who cannot use the double weapons and either HAVE to go exotic for 2h feats for offhand or use weapons much smaller than they.
Edit: So too, like bastard sword and katana it would benefit from -twohand like the other two did, but was alone in the exception of not benefitting from 2h feats, thus a disparity another.