noun
simpleton; henpecked husband; sniveler
Derogatory term for a weak, ineffectual man, especially one dominated by his wife. The image is of a person who can be beaten with two sticks and still not fight back.
あの男は完全に二本棒で、妻に頭が上がらない。
That guy is a total henpecked husband; he can't stand up to his wife.
noun
two-sworded samurai
Historical term for a samurai who wore two swords (long and short), as was customary for the warrior class. Rare and archaic outside historical contexts.
江戸時代、二本棒は武士の身分を示すものだった。
In the Edo period, the two-sworded samurai was a mark of warrior status.
Also means coward, but emphasizes lack of courage rather than being dominated by a wife.
Literally 'two sticks'. The figurative meaning likely comes from the idea that a person who can be beaten with two sticks and still not resist is a weakling. The historical sense refers to the two swords worn by samurai.