Tier 2 shows buildable...burns the supplies and shows available. Until you leave the building screen. The weapon built isn't in inventory, and returning to the build screen, the weapon shows with nothing built.
Haven't tried tier 3 for...obvious reason.

the tier 2 disappeared.

I tried building the tier 2 versions of these and they disappeared.

Correct

I don't need this mod if I disabled the weapons with another mod Right?

Oh right. This mod also adds in the weapons, right? I was thinking this messes with the outfits or something at first. lol