London, Coventry and other UK cities were never Battlefields in WW2, but that didn't stop the Nazis from dropping bombs on non combatants, including women and children. 

The Nazi Armed Forces used a number of means of killing Jews and others. Poison Gas was just one of the weapons they used. Other weapons included firearms and vehicle exhaust. A weapon is something used to kill. Nobody would try to use a captive bolt gun in battle, but it is still a weapon used to kill cows and other livestock.

Do you claim that the firearms, including automatic weapons, used to kill Jews and others were not weapons because they were not being used on a battlefield at the time?