Client-sided hacks?

Sup!

I came here cuz i wondered if somone that knows how to make items have custom stats without touching the server like something that's client-sided. I would really be thankful if someone could help or share a tutorial of this.

Not sure how this is related to private servers but you can edit the client XMLs for a client sided effect.

You can't gain anything by doing this. The effect is purely cosmetic. If you try to use the weapons on enemies, you will get disconnected for certain effects (e.g. rate of fire) and desynced for others (e.g. damage; results in invisible enemies).