'ashed' is formed in English by adding the past-participle suffix '-ed' to 'ash' (the noun/verb).

'ash' comes from Old English 'æsc' meaning 'ash (tree) or ash wood', from Proto-Germanic '*askaz'; the modern adjective and participial form 'ashed' derives from this noun/verb base plus the English '-ed' suffix.

Originally related to the ash tree or ash wood, 'ash' later broadened to mean the powdery residue of burning; 'ashed' developed to mean 'covered with ash' or 'reduced to ash' accordingly.