Does this edge only work PvP? I have it and haven't noticed any difference in melee., even when it's lightning around me. I imagine the effects are small but I was hoping they'd at least be noticeable and that hasn't been the case thus far.

It works on anyone.

Consider that you can't really tell whether you just wore a wide copper or not from watching your melee. You're not going to get +20 damroll or whatever from an edge.

That it's such a small bonus that it's not noticeable on Players with any Damage reduction.