They no longer appear to be anywhere in T2 or T3, for whatever reason.

Why not place them in T2/T3, heck maybe even T1 Treasure Vaults?

T1 could drop a Drake Scale Shield, T2 Stone Tortoise, and T3 Omega Shell.

Have 'em appear in Treasure Vault 25~50% of the time, and drop their shields at the same percentage as they normally do.