PIE *bhel(輝く、閃く)から。閃光を放つ、眩惑する、見えなくする、という意味。blindは語彙発展の結果。語源はblendと同じ。
The twilight, or rather the hour between the time when one can no longer see to read and the lighting of the candles, is commonly called blindman's holiday. [Grose, 1796]In reference to doing something without seeing it first, by 1840. Of aviators flying without instruments or without clear observation, from 1919. Related: Blinded; blinding. Blindman's bluff is from 1580s.