Really not sure what you are asking... Every character has 3 weapons: primary, secondary, and heavy. Melee is not included in those, and we do not know if you can change the time of melee weapon. However, it appears that each class has its own type of melee. The hunter uses the knife, edgewalker skills focus is the arcblade which is a massive melee with the hunters' knife that seems to have some sort of electrical element added to it. Goldengun is a summoned hand cannon, does not matter what weapon you are using at the time, with 3 massively powerful shots and is range. That is basically what we know so far, without getting into details. To say which is better with out any more information is pure conjecture at this time. Both will do tons of damage, and I would go so far to say that arcblade will do more damage just because of the risk vs reward idea, but that is my opinion.

My big doubts are different. I for one want to use edge walker, but I have yet to see the advantage over golden gun. Golden gun gets 3 shots which are range with a short aoe explosion, on the other hand edge walker from what we've seen, you kinda hit like single target around 3 times really fast. My problem is both have around same number of target hits, both do good damage, but golden gun is ranged and safer. I hope some perk can make me go straight to edge walker without it been weaker than golden gun, unless edge walker have extra damage then I doubt it.

We didn't know whether melees can be modified or melee weapons equipped, but melees might be tied to the focus or upgradable or something like that. I don't think they've said anything about that. We know that the classes have different melee attacks; the hunter has a throwing knife that is probably tied to the focus as well as a regular melee, the Titan has a regular melee and a shoulder rush thing which I believe is tied to the focus, and the warlock has a sort of draining magic melee that we don't know much about. As for the arc blade, I fully expect that to be independent of any melee weapon/upgrade/etc. the user has. Ghost gun (the Gunslinger super) doesn't need a hand cannon equipped, so I assume that arc blade won't need a knife.