Answer:
My first is in wield, sever bones and marrow. My second is in blade, forged in cold steel. My third is an arbalest, and also in arrows. My fourth is in power, plunged through a shield. My fifth is in honor, and also in vows. My last will put an end to it all.
Gets rid of bad ones, short and tall. Tightens when used, one size fits all.
What has two legs but doesn't walk?
When it comes in, From sea to shore, Twenty paces you'll see, No less, no more.
It is sometimes known to have silver linings.
You use it between your head and your toes, the more it works the thinner it grows.