Lets face it, few use plate shields of any kind.
Even the end results are kind of meh.
Why not give the shields a buff?
Give Volcanic plate shield an elemental resist bar (equal to the pierce resist of the IronMight), and give the Ironmight another Status (Freeze resist for example since no other shield has pierce and freeze naturally).
Since these are Shields you won't hear anyone in the LD community complaining and this buff would certainly encourage players to get one or both (for Vana and Ice Queen).
People get the volcanic plate shield because of the fire resistance honestly. Ironmight doesn't really have anything going for it but if you buff one the other should be buffed too. Maybe just increase both of their base health and call it a day.