B.E.A.S.T Did I waste my Marks on a Shield?

Durandal

So really getting into the BEAST, loving the idea of it.  And I thought, I mostly use my Minigun, so I'm going to turn in the wristblade for a Shield.  I admit I didn't ask before I purchased, so it's my own dang fault, but is there supposed to be some armor bonus to having it that I'm not getting because I'm not using right or is it PURELY for the attack skills under MWP?

Maruna

All mounted things are purely for using their skills. It's not like a shield in other games.