I've been wondering... the sword/knife that is able to kill mga kerubin (the one uriel used) does it belong to Michael or Lucifer? (I cannot seem to remember. I must have missed something)

**** DO NOT READ IF YOU HAVEN'T WATCHED TILL SEASON 5 EPISODE 9!!! YOU HAVE BEEN WARNED.****

Actually, it's not the kutsilyo that killed Uriel. It has been mentioned that only an angel is able to kill another angel [as shown sa pamamagitan ng Dean stabbing Cas with Ruby's kutsilyo in the first episode of season 4 with Cas feeling no effect]. It is the same as Cas killing his fellow two mga kerubin in season 5 with another type of knife. The kutsilyo that killed Uriel belonged to no one at all. It could've been Uriel's for all we know.


Hope my answer helped!