Can't find any reference in the game for warp weapon and what it to vehicle armor. Example a deamon wepon or psy power that as the quality warp weapon does it negate the armor facing or what. Seems like his would be way to over powered.

Considering that BC has no vehicle rules at present, this is somewhat understandable. It is, however, something that probably should be incorporated into OW… *scurries off to there*

You have 3 options for resolution. Ignore Warp Weapon, Use Warp Weapon as Written, Compromise.

Ignoring it you argue that a vehicle's armour is too thick and that the Warp Weapon attribute just doesn't cut the muster anymore. This could be a problem as a Terminator approaches a light vehicle in armour strength.

You can use it straight up. In this instance the Warp Weapon becomes incredibly useful in an anti-vehicular role.

Or you can compromise. Personally I'd go for halving the armour attribute vs Warp Weapons. On the larger tanks, it still shouldn't be too much of a problem, but against the lighter vehicles, it should do it's job.

It went well in session. I ended up halving the armor facing for warp weapon. Didn't seam to brake the game. Group was confronted by a librarian dred. The fight was epic. If i had wanted to stomp them ignoring the weapon would have forced them to face the dred another way.