sickle
銍 centers on a sickle, a curved metal blade used for cutting crops or grass.
銍 combines 金 (metal) with 至, which likely contributes the sound. The character is used for a metal sickle.
The left side is metal 金, and the right side 至 looks like a curved blade reaching down. Picture a metal sickle cutting through crops.
For チツ, imagine a sickle that makes a sharp 'chits' sound as it cuts through stalks: chits -> チツ.