Unexpected Loot
After looting the ship of the Ox Head Pirates and getting the proof of their successful hunt for the captain of the Ox Head Pirates, Samiel ordered Captain Alvar to sink the ship of the Ox Head Pirates because there was nothing else they could do about it.
After the ship was sunk, Samiel departed to his chambers to count the gains and check on the Magic Tomes he obtained from the Ox Head Pirates because Juulius brought him more than a hundred Magic Tomes from the ship.
If he had to guess, the Ox Head Pirates must have robbed somebody who was transporting them for business purposes, so they were pretty lucky. It was possible that they managed to catch the ship of some merchant that was transporting them or some collector.
Magic Tomes were rare merchandise and they sold well for high prices, especially in the Tower or more developed civilizations. They were the basis for the magical education for all Paths of Magic, so there was a constant need for more and more of them.