I just finished reading a progression fantasy that tackled this exact premise, and it surprised me how different it felt from the usual revenge-power-fantasy mold. The protagonist kept all his old-man assassin memories but was born into a noble family this time. Instead of just hunting down his old betrayers, which he does methodically over decades, the story became about him using those cold skills to protect his new, fragile family. He's calculating poison dosages for political rivals one chapter and awkwardly trying to learn how to be a good brother the next.
That tension between his past-life instincts and his current-life attachments is what makes it work. The redemption isn't some grand, sappy forgiveness arc. It's quieter. He starts viewing the world not just as a series of contracts and targets, but as a system he's now embedded in, with people he'd actually mourn if they were gone. The revenge plot almost becomes background by the final volume, more of a loose end he needs to tidy up so he can finally live peacefully in his second chance. Makes you wonder if revenge for a guy like that is even the point, or if it's just the last bit of cleanup from a life he's already left behind.