Seirei no Moribito, Blade of the Immortal Recommendations
Both anime have a capable warrior becoming a bodyguard of a youth. They are both set in a historical setting (old Japan for Blade, and a fantasy world that does have a lot in common with old Japan for Seirei).
There are some good fighting scenes in both anime and the villains get character-development as well.
Both are set in an older setting similar to old Japan, both use swords and other bladed weapons as their main weapons. They both also deal with making amends for lives that they have taken.