Manubrium, directly from the Latin for handle, manubrium, which in turn comes from the Latin words manus, hand, and hibrium (from the verb habeo, "I hold").
Since the times of the Romans the sternum has been likened to a sword, the gladius of the gladiator. Its "handle", the manubrium, is the sternum's most superior region, located just below the neck. A sharp tip, the xiphoid process (which comes from xyphos, Greek for sword) is at the inferior end. Between the two structures is the body, an older term for which is gladiolus (Latin for "little sword.")
A related etymology: in some species at least, the cluster of flowers, or inflorescence, of the genus gladiolus resembles a short sword; an ancient name for the plant was xiphium. It is also known as the "sword lily".
A typical sword, or gladius, of ancient Rome. (Drawing by the Swiss artist Gerzi, 2004).
The sternum; using the sword analogy note how the manubrium is more akin to the knob (pommel) at the end of the sword's handle rather than the handle itself, and that the facets on the body suggest the handle's finger-grips. From www.pdh-odp.co.uk
A common name for the radius among the Romans was the "manubrium manus", or handle of the hand, as it is the radius and not the ulna that articulates with the carpals.
Other words derived from manus and all related in some way to the hand: manual, maneuver, manuscript, manipulate, and manufacture.