Proxys are thing that are used to represent anoth difrent thing. below is a selection of what can be represented by variouse units and weapons.
Drone- infantry, tanks, APC
Light mech- Super heavy tanks, power armoured infantry
Spider mech- realy large flyers, land battleships, massed Infantry
Mech pistol- massed rifle fire, RPG, tank shell
knife- lots of Close combat troops franticly trying to kill a mech (idiots)
Chainsaw- circular saws, jackhammers, constant energy discharge weapons (big ass tasers)
Hammer/Axe- polearms, piledrivers