1. First Blade, Only Brother
That blade had done something to Dean, but he wasn't sure what. When Magnus first forced it into Dean's hand, it was as if the handle snapped into place in its owners grasp. At first it hurt, but then the pain went away and it was replaced by an obscene amount of weight that was pulling his arm straight down. Dean wasn't expecting the blade to be the burdening factor of this whole deal, and it honestly scared him. The power continued to course through his veins long after Dean had dropped the blade unable to hold onto its weight any longer, but Dean was frozen in place pinned against that wall. Dean didn't like how the first blade made him feel, but he still craved to feel what it made him feel again; he craved HIS weapon.
Sam came back to save Dean, but as per usual got himself caught and sliced up like a Thanksgiving turkey and deep down Dean knew that was going to happen, that Dean would be the one saving his little brother tonight. While Magnus was slicing up Sam, Crowley had managed to free Dean and he jumped towards the blade without a moment's hesitation. The first blade locked into his grip and felt better in his hands, it only tingled his arm this time, it felt so god even after Dean sliced Magnus's head off his too poised body. The blade felt so right to Dean, that no matter how he tried or thought about it he couldn't put that damn thing down! Even after the chopped head had rolled over to Sam's feet and its eyes were staring a hole right into his soul, Dean could not for the life of him drop that knife. It took the thought of killing Sam to scare Dean enough to want to put the first blade down.
"Dean!" Sam barked trying to break Dean from his trance.
"Sammy's right, I need to put this thing down before I do chop Sam up" is all Dean could think as Sam was yelling at him. Dean had finally dropped the blade and allowed Sam to carry it back to the car, even if it angered him for some odd reason.
"Sam" Dean said breaking the tension in the car after Crowley had managed to steal the blade back, "once we gank Abaddon, do me a favor and find a way to get this damn thing off my arm."
"Sure Dean" Sam said reflecting back to the look in Dean's eye before he dropped the blade. Was Dean going to kill him? What was going through Dean's fucked up head? The more Sam thought about it, the more it scared him.