Officers are always +1 on the force level. If you are combative, they use mace/taser, if you have a knife they use a gun, etc.
The only exception to this is when an officer has backup on scene and they can coordinate enough to allow one or more to provide lethal cover (guns) while the others try to employ less lethal tactics (taser, mace, beanbag shotgun, etc). This way, if those less lethal items dont work (and they dont 30% of the time) they are not scrambling for their gun while a pissed off suspect is charging with a knife.