no....you dont must edition your weapon.wdl.

You must only change x,y,z coordinates in the room
for your weapon.

look for in the player template.

for example:

open the Project menager in WED...
up to Customize....search it in Bibed player weapons..
PlBipedWeap00_WeapP

or...

look into WED...
Click on your weapon and look left side
to the behavour panal.