expression
neither one thing nor the other; too short for a belt, too long for a sleeve tie
Idiomatic expression describing something that is awkwardly in-between and not quite suitable for any purpose. The literal image is of a cloth that is too short to be used as an obi sash but too long to be used as a tasuki cord.
この企画は帯に短し襷に長しで、採用するかどうか迷っている。
This proposal is neither one thing nor the other, so we're unsure whether to adopt it.
彼の経歴は帯に短し襷に長しで、どの部署にもぴったり合わない。
His background is too short for a belt and too long for a sleeve tie—it doesn't quite fit any department.
中途半端 is a more common and direct way to say 'half-baked' or 'incomplete', while 帯に短し襷に長し is a proverbial expression emphasizing the awkward in-betweenness.
A traditional Japanese proverb. The literal meaning is 'too short for an obi, too long for a tasuki', referring to a piece of cloth that cannot serve either function well. The exact origin is uncertain, but it has been used for centuries to describe things that fall awkwardly between two useful states.