I do not know the reason behind it... Or if it has been fixed prior to my post. Whenever you get killed - sometimes you will come back only with a knife and can no longer use it regardless. The second issue is when you get dropped/timed out/host lost connection from a game - the class resets itself...
When is the last time you played?
All the PK issues have been fixed to my knowledge.
just happened to me tonight host migration and peacekeeper disappeared left with knife and couldnt pick it again.Next game it was back everything ok.