*ghabh-

"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]

1650s, misspelling (with French du for de) of Middle English avoir-de-peise, the Norman form of Old French avoir de pois "goods of weight" (equivalent to Medieval Latin averia ponderis), from aveir "property, goods" (noun use of aveir "have," from Latin habere; from PIE root *ghabh- "to give or receive") + peis "weight," from Latin pensum, neuter of pendere "to hang, cause to hang; weigh; pay" (from PIE root *(s)pen- "to draw, stretch, spin").

The oldest sense in English is "goods sold by weight" (early 14c.). It is attested from late 15c. as a system of weights in which 1 pound = 16 ounces; introduced into England from Bayonne, from late 15c. it was the standard system of weights used in England for all goods except precious metals, precious stones, and medicine.