The disabling of Kleiner Cannon and other PTSD SWEPs was due to loading related issues with that weapon pack. I am sorry for the inconvenience and long delay however you will be able to use these weapons on restart.
Knives are a tricky topic and I can't resolve that one right now unfortunately.
I remember when the Kleiner Cannon was out... everyone shooting it, having fun. Till it got blocked for some months then unblocked then blocked. I just want it to be unblocked for having banned for sucha long time. don't even get me started on the ursus knife...