How can it be made clear?
The ARC doesn't make sense to me. There's nothing about the ARC that tells the player "Hey, this thing can shoot through walls". Right now it says "This is a big cannon" and you assume it works like a regular cannon that has to have line of sight to hit targets.
How, without changing the ARC significantly, could it be made more clear to the user what the ARC does and how it manages to shoot through walls?
Bonus points if you can explain the mechanism of the arc's whimsical disregard for solid material obstacles.