Armorpede is an enemy exclusive to the PSP version of Final Fantasy IV: The After Years. It appears as a rare enemy in Yang's Challenge Dungeon. Its defenses mean that it is near-impervious to regular damage, so Ursula should use her Tenketsu ability (or the Five Star Crimson Palm Band) to guarantee a kill. It generally fights by using normal physical attacks against a party member, and if hit by any magic attack, will counter by using a strong Pincers attack.
Killing Armorpede will guaranteed to reward one of its item drops.