Weapons and Armor balance

Hello guys, let's assume we have a game like a WoW, with tons of weapons and other items. It's all good until you have to give different purpose to different items and stats.

For exampe:

1. We have a dagger (2 attacks per second with 10 damage), and we have an axe (1 attack per second with 20 damage)? What is the point? When dagger will be better than axe and when axe will be better than dagger? My thoughts - dagger will be better when we have special effects on every attack not depending on damage. Axe will be …