write, draw, sketch, compose
冩 centers on the act of putting marks onto a surface to create a visual or written record: writing, drawing, sketching, or composing.
冩 is a variant form of 寫. The older form 寫 combines 宀 (roof) with 舄, which likely contributed the sound and the idea of placing or setting down, later extended to writing and drawing. The modern 冩 replaces the roof with 冖.
Under a cover 冖, a hand-like shape 臼 and a wrapping element 勹 work over fire 灬 to inscribe or sketch something onto a surface.
For シャ, imagine a sharp pen sketching a picture: sharp -> シャ, and the pen writes and draws under the cover.