The Mirror Shield of the Well is a unique, rounded reflective shield. It is equal in strength to an Ebony Shield, with the weight of a Dwarven Shield. The shield is classified as light armor by default, but can be converted to light armor at an Alteration Table.
The shield is found in Yngol Barrow, wielded by a Woeful Dragur guarding the long stone bridge just beyond the first puzzle room.
The shield is included in the Mirror Shields video, and is the second shield featured: