Here all of the damage is worked out.

Weapons:

Wooden Sword: + 10 Damage
Samurai Sword: + 15 Damage
Shortbow: +10 Damage
Longbow: + 15 Damage
Katar: + 12 Damage
Claw: + 14 Damage

Armors: (Armor decreases the damage you take from opponents)

Regular Clothes: -2 Damage
Karate Outfit: -5 Damage
Samurai Outfit: -6 Damage
Ninja Outfit: -6 Damage

Accessories:

Battle Vizor: -1 Damage

More?

There are still things to come.