Dual-wielding is pretty weak in dnd 5e tabletop. Attacking with an offhand requires a bonus action, which kills it right away for many classes(hexblade warlock, paladin, monk, ranger). And it scales pretty badly too compared to polearm master or great weapon master feats, which boosts your big heavy axe damage a lot.
So my suggestion is this: how about making an offhand and main hand attack as a single action once per turn(so if you are a 5 level fighter only your first attack will be with two weapons). What do you think?
