early 14c., from Old French (h)able (14c.), from Latin habilem, habilis "easily handled, apt," verbal adjective from habere "to hold" (see habit). "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., but some derivatives acquired it (e.g. habiliment, habilitate), via French.
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]
word-forming element expressing ability, capacity, fitness, from French, from Latin -ibilis, -abilis, forming adjectives from verbs, from PIE *-tro-, a suffix used to form nouns of instrument.
In Latin, infinitives in -are took -abilis, others -ibilis; in English, -able tends to be used with native (and other non-Latin) words, -ible with words of obvious Latin origin (but there are exceptions). The Latin suffix is not etymologically connected with able, but it long has been popularly associated with it, and this has contributed to its survival as a living suffix. It is related to the second syllable of rudder and saddle.