weapon upgrades

[desert tree]

How do I upgrade my weapons

[tough egret]

technically getting better armor increases power multiplier, increases damage, which is technically a weapon upgrade
in vanilla, you need to work your way up to a vault and do that, but those are t6/7
so complete the story first and you will learn

or you make better ones at an anvil

[desert tree]

I maxed the anvil but I saw that I need an add on how do I get that?