Do you want to change the "hit" only or also skills?
Changes at the stated functions for hits and arrows (example on arrow):
Do you want critical and so on to also work or to always 1 damage, independently of critical, penetrate, etc?
If you want ONLY 1 damage to mobs (hits, skills, criticals, etc), ignore the previous steps and
Go to char_battle.cpp, in the damage function, edit like on image: