often habiliments, early 15c., ablement, "munitions, weapons," from Old French habillement, abillement, from abiller "prepare or fit out," probably from abile, habile "fit, suitable," from Latin habilem, habilis "easily handled, apt," verbal adjective from habere "to hold" (from PIE root *ghabh- "to give or receive"). An alternative etymology [Barnhart, Klein] makes the French verb originally mean "reduce a tree by stripping off the branches," from a- "to" + bille "stick of wood." Sense of "clothing, dress" developed late 15c., by association with habit (n.).
"having sufficient power or means," early 14c., from Old French (h)able "capable; fitting, suitable; agile, nimble" (14c.), from Latin habilem, habilis "easily handled, apt," verbal adjective from habere "to hold" (from PIE root *ghabh- "to give or receive").
"Easy to be held," hence "fit for a purpose." The silent h- was dropped in English and resisted academic attempts to restore it 16c.-17c. (see H), but some derivatives (such as habiliment, habilitate) acquired it via French. Able seaman, one able to do any sort of work required on a ship, may be the origin of this:
Able-whackets - A popular sea-game with cards, in which the loser is beaten over the palms of the hands with a handkerchief tightly twisted like a rope. Very popular with horny-fisted sailors. [Smyth, "Sailor's Word-Book," 1867]