one solution i found was to use a bone on the player hand. it's better than attaching it to a vertex because the bone also has direction, so you just set the weapon to the bone's position and direction. another good point is that you can get the bone by name, and not a number, so if you have more than one model that can be holding the weapon, you don't need to get the vertex number for each model, you just need that all of them have a bone with the same name...