段階
だんかい · dankai · JLPT N2 · noun
stage
🪜 段 = step + 階 = floor/stair, so 段階 = steps of a staircase = stages
It is 階段 (kaidan, stairs) with the kanji order swapped. Each rung is one grade, and moving up them is progressing through stages.
段 — left component 𠂉 + right component 殳 (weapon/strike)
段 originally depicted striking or hammering a piece of stone or metal with a tool, shown by the 殳 'strike' element on the right. From this 'hammering/forging' sense it extended to mean a section or segment cut off, and today it commonly means a paragraph, stage, or piece.