how do u edit skins to add weapons

ok i wanna edit a model and add a sword in its hand?

Either attach the sword model using Special Effects or add it to the model directly.

If you want to directly edit the model, look in the modelling forum.

well i already checked the special effects already and i didnt fidn anything i wanted so im gonna have to do it directly

You don't have to do it directly...
You can download weapons to attach here