You can modify the data, you can modify the files in "LonaRPG\Data\Effects" to achieve your goal of increasing the attack power.
The "Weapons" folder is the basic data of your weapon, it determines the weight of your weapon and the values you have after equipping it, such as movement speed, ATK, DEF, and you can even add the "sexy" value to make the weapon equipped to increase the sexy value.
The "Skill" folder is for weapons and skills that come with some races. By modifying it you can change the STA that a skill consumes when used, or the damage it does on the target, or you can even change it to increase the STA by attacking instead.
The other folders are the same, I think you just need to study carefully to figure it out.