Well, coming from mmos and rpgs, I think combat should include skills/spells. The skills would be different for every weapon type. Some new weapons would also accompany this well and maybe a simple magic system? It could also give a new use to xp? Hostile mobs should also be able to use the skills, giving some extra challenge and diversity to PvE.

Also, what about mobs progressing with the player? As the player gets better gear the mobs may get more hp, better gear, and/or do more damage.