Heyitsjiwon
One Thousand Club
That's never gone wrong before.He's got arms and armor. His men called him Sir so presumably he's been knighted, he could easily enter service with another Lord. If his father refuses to ransom him, I'll simply force him to renounce any claims from him or his children to the territory I conquered in exchange for his freedom. Then he can either take up his sword as one of my Knights or I'll like exile him to Dyrnwald or something.