My thoughts exactly. I loathed Zeppel after the end. To betray his own students like that...especially poor Vayne...was just unforgivable.
If you play Mana Khemia 2, you'll see that he retains his cowardly persona to a T, even after (somehow) becoming principal of the school. --- "Just watch me, I'll become the God of Death once again...but right now, I need some sleep."