noun, noun or participle which takes 'suru', intransitive verb
assistance in a fight; backup
Refers to helping someone in a physical fight or conflict. Often used in historical or dramatic contexts, but can appear figuratively. Can be used as a noun or with する to mean 'to assist in a fight'.
彼は喧嘩で友達の助太刀をした。
He backed up his friend in the fight.
時代劇ではよく
In period dramas, scenes of fighting assistance often appear.
noun
helper in a fight; supporter
Refers to the person who provides assistance in a fight. This sense is a noun only, not used with する.
彼は頼りになる助太刀だ。
He is a reliable backup in a fight.