I know you can use create homebrew magic items to create common items.  But it requires a base weapon as a template.  There is no way to customize weapon stats to create new weapons say that do 2d4 damage for example, as no base weapon used 2d4 as a damage base.   Which means using a base weapon that has different stats does show up on the character sheet attacks correctly... unless you go through there to create a whole custom item using the exact method I'd like to see in the homebrew creation.

While initially not planned, the more recent dev update streams have stated that they now do plan on allowing us to homebrew base weapons at some point. No ETA, but it will likely be after they release other requested features.