Just finished the series on first watch. Have a question here:

Just watched this series. Loved it. New favorite anime. Can't say enough how great it is.

S4 E14 is when we learn the Erin radical group has betrayed the military. When Zeke's wine poisons the eldians and turns them into pure titans, Levi fights his whole squad turned titans, then defeats Zeke. He has him beat but decides to let him live...

Theres no way Levi shouldn't have killed him right then and there. He's beat Zeke before and he got away, so he should know what Zeke is capable of near death. Levi should have decapitated him so there was no chance he could become the beast titan again. Why would he risk this chance (and then Zeke gets away and nearly kills Levi)?