The 3rd topmost badass elf must have been Finrod Felagund, who engaged on the quest for the silmarils, and met his demise in the pits of Sauron on the Island of Werewolves. Notable achievements: a spellsong contest against Sauron, where the 2 battled with the magic of mind-probing and self disguise, as he was trying to keep the magic orcish disguise cast on himself, Beren and Luthien (that was like the "Superball" of bardic enchanted music, i mean, he disguised LUTHIEN as an orc...make me believe that!).
Felagund was like a million dollars then, but he still lost, almost mind flayed. Later, when the wolves were approaching to eat them alive, as he was already starved and wounded, he BROKE the chains with his bare hands and wrestled with 1st age bloodthirsty wolves under the command of Sauron to buy some time for Beren and Luthien. While doing that (as we have seen with Kazumi and Daigo in OOTS), is an automatic death sentence, it is still a remarkable achievement.
And yep, Narsil was among the most powerful blades ever. At least, among those that did not backbite its wielder. 2 palms above were the star iron blades, Anguiriel and Anglachel/Gurthang, and possibly Aranruth, the sword of Elu Thingol, which later on became "THE" sword of the Kings of Numenor, and was lost "when the oceans drank the Island" (nod at Conan).
O.