mid-13c., pomel, "ornamental knob or ball, decorative boss;" c. 1300, "knob at the end of the handle of a sword hilt or the grip of a dagger," from Old French pomel (12c., Modern French pommeau), "rounded knob," diminutive of pom "hilt of a sword," and directly from Medieval Latin pomellum, diminutive of Latin pomum "apple" (see Pomona), the connecting notion being "roundness." It serves to keep the hand from slipping and for striking a heavy blow at an adversary too close for the sweep of the weapon.
The sense of "front peak of a saddle" is recorded from mid-15c. In 15c.-16c. poetry it also sometimes meant "a woman's breast." The gymnast's pommel horse "vaulting horse" is so called by 1908, for the removable handles, which resemble pommels of a saddle (and were called pommels by 1887).