Thaumaturge Mirror shield

[orphias]

A thaumaturge in my party wants a mirrored shield so he can use it as his "Mirror" implement. His reasoning is the old medusa lore and the mirrored shield idea. Any advice or thoughts on this would be appreciated.

[Dr. Frank Funkelstein]

There are some rule parts that hint at other intentions:
"thaumaturges always choose small, portable, handheld mirrors as implements"
"While an implement is useful to you, it typically has no value if sold"
"a special object of symbolic importance"

More important is the restriction on hand usage from implements empowerment:
"You don't gain the benefit of implement's empowerment if you are holding anything in either hand other than a single one-handed weapon, other implements, or esoterica, and you must be holding at least one implement to gain the benefit."

Ruling that a shield could be used as an implement would circumvent this restriction. I can understand that this would be nice for the player, but don't think it is the intent of the rules.