Rurouni Kenshin: Meiji Kenkaku Romantan, Stranger: Mukou Hadan Recommendations
Both involves sealed sword and passionate samurais.
Samurai era period with a main character so similar to Kenshin. An extremly skilled warrior haunted with a dark past for what he has done, now seeks and finds peace in atonement for his deeds.
Both shows are samurai dramas based on historical facts, with some cool action, however S:MH is a bit more realistic and brutal. Although plots are a bit different, but Kenshin is basically the same character as Nanashi. Both of them are ronins who regret their past. Even though both of them were extremely skilled assassins in past, in current era they avoid to kill people no matter what.