It should work as health or energy pack. You equip it in your inventory as a consumable item. WC should work like this instead of passive core. You have to replace your primary passive just to use this core and sometimes is not worth it. What if you buy massive strike for example. Varium limited core, is not worth at all to replace it with a x10 passive.
You are already paying 2k credits for WC, you don't have to lose more than that. This passive doesn't give you any advantage in battle, so why it should also give you a disadvantage?
Price could be increased if you want to compensate this buff.
Or at least, WC could be equiped in any weapon you want. Is not the same to equip it in your primary than equip it in your gun/aux.