Answer:
Slayer of regrets, old and new, sought by many, found by few.
who do you think you know but sometimes you don't
Who is he that runs without a leg. And his house on his back?
You are having a bad day if 12 peers deem you to be this
A dagger thrust at my own heart, dictates the way I'm swayed. Left I stand, and right I yield, to the twisting of the blade.
People take me on walks and I run and have fun. What am I?