Energy edge reduces your mechanical damage slightly, but overall gives you a lot of energy damage in return, which is even more useful against enemies that are resistant to mechanical damage like robots. But overall there is no reason not to put additional damage on you weapon. I would recommend having one weapon with edge and one with shock, since there are some enemies resistant to one of them but not other. Also, energy is better against single targets, shock is good against crowd that is closely placed together.
There is one little downside is that you will need electrical kits to repair your weapons, not mechanical ones. Usually mechanical scrap is easier to aqcuire, since there are much more mechanical stuff and most of it you would not regret recycling, while a lot fo electrical stuff is sold for good money, meaning that you feel regret recycling them.
