considering that Bungie has already announced that the Fallen Captain is a very fast, close combat enemy (and also the fact that he obviously has two swords that seem to have some kind of energy around them) I would expect that we would be given some kind of last resort to fend them off, even with something more CoD knife style. I personally wouldn't mind having some kind of primary melee weapons in Destiny, but they can't just be thrown in there like "Well why the hell wouldn't a large armored space soldier with advanced technology suddenly pull out a flaming katana and bull-rush a Cabal?" They have to make it flow with the rest of the game.