Really like the sound of this. The only things I'd say from a logline perspective is that it's a little long but I fully appreciate the need for all that info in the inciting incident.
From a story perspective, why is he "forced" to do something? Protagonist - proactive and all that. Can he not voluntarily take up the mantle because he wants to show his former boss that he's more than just a henchman? Externally he wants revenge, internally he just discovers that he just wants to be a good guy.
I think Adam makes a valid point. It might be worth clarifying a setting - in my head it's a fantasy version of the Middle Ages - knights, damsels in distress, dragons, magic. Kinda Shrekian I guess haha.