Hu ?
You are able to trad the Hermit weapon from the last event to add them stat. The Trad option is in living then action tab then Weapon Trade. Here you will be able to add start to the Hermit weapon.
The % damage increase works on basic damage. That means the damage you have when you don't put any weapon on you char.
THere is also "increase weapon damage by X%" Only the damage from you weapon are boosted.
The better damage boost are "damage increased by X% on critical hit". The tips is make sure you have the maximum of critical rate (10000/10000) and then boost the damage on critical hit.

*Moved to Game Help section*