Sentence:  Orion hit a rabbit once; but though sore wounded it got to the bury, and, struggling in, the arrow caught the side of the hole and was drawn out. Indeed, a nail filed sharp is not of much <WSD>avail</WSD> as an arrowhead; you must have it barbed, and that was a little beyond our skill. 
Meaning of the word marked with <WSD> tags:  Effect in achieving a goal or aim; purpose, use (now usually in negative constructions). (from 15thc.)