It seems that the Festive Crusader's crossbow doesn't get the +10% Uber on hit
That is pretty much it.

like festive flare doesn't make you flare jump.
but festive GRU drains your health like original GRU

Please see this forum post from Frog http://www.thehh.co.uk/forum/viewtopic.php?f=72&t=10971

Festive weapons have unique item ID's that have to be added in order to get the same effects as the normal version.

You will need to look up the item number for the missing festive weapons and reply to this thread with them.

So here are the numbers:
Festive Flare gun: 1081
Festive Flare gun: 1079
Festive SMG: 1149
Furthermore I have not found more of these bugs, Ill try and find more of these later