I had one drop off a battle-scarred bazu last night. Ive spent alot of time in NC. Ive killed alot of murks, ferans, and dragorns of all kinds and never seen it. Ive had 2 kyanites, one cape, 2 discordant scorae, and 3 slugworms drop in the time ive spent there...... but no shield. Then when i least expect it, it finally dropped. I had given up on it a while ago. I sure as hell felt good when i saw it.
Don't go to NC expecting to get this shield within a reasonable amount of time.