Yeah, I think it should totally be able to do that. I'll have a look sometime soon to see about adding that in. In the meantime, today I just posted an updated version of disarm on the Disarm page, let me know if you encounter any bugs in it.
But I mostly just slapped its existing code onto an updated set of warcraft libraries, and forgot to check back here for messages like this one! So today's update doesn't have that feature but maybe I'll get it in soon.
Update: Actually, there is kind of already a button for this! If you do "Edit > Isolate Part" and type "weapon" in the box it lets you make a model of just a weapon.
However, this does not delete animations and other extra data from the model file. So I might add a feature to clean those out.