ḱeh₂-p-tro-
“grasping tool, handle”haft, have, heavy, heave
Instrumental of *ḱeh₂-p- yielding English haft, have, heavy, heave from sense of grasping/lifting.
Discussion
The PIE form *ḱeh₂-p-tro- (grasping tool, handle) derives from the verbal root *ḱeh₂p- (to seize, to grasp), with the instrumental suffix *-tro- creating a noun of means: "the thing by which one grasps." This is a tool-word, and its descendants preserve the concrete image of the closed hand across remarkably diverse semantic domains.
The Germanic reflexes are among the most basic words in English. Have (OE habban, from PGmc *habēną) continues the root with the meaning "to hold, to possess" — having is the state resulting from grasping. Heavy (OE hefig, from PGmc *habīgaz, "having weight") is literally "full of having" — that which you strain to hold. Heave (OE hebban, "to lift with effort") preserves the physical act of grasping and raising. Haft (OE hæft, "handle" — the part you grasp) is the most transparent continuation of the *-tro- tool-word itself.
The semantic chain from "grasp" to "have" to "heavy" illustrates a fundamental conceptual development: possession begins as a physical act (seizing), becomes a legal/abstract state (having), and the difficulty of the physical act names the quality of burdensome weight (heavy). English encodes an entire philosophy of property in three words from one root.
Latin capere (to take, to seize, to grasp) continues the root with the expected Italic treatment and generated one of the largest derivative families in English: capture, captive, capacity (the amount that can be held/seized), capable (able to hold/take), accept (ad-capere, to take toward oneself), conceive (con-cipere, to take together — an idea "taken together" in the mind, or a child "taken together" in the womb), deceive (de-cipere, to take away from, to ensnare), except (ex-cipere, to take out), perceive (per-cipere, to take thoroughly, to grasp with the mind), receive (re-cipere, to take back), and recipe (literally "take!" — the imperative of recipere, the instruction at the head of a medical prescription).
The word captain (from Latin caput, "head," which some connect to this root through the "seizing" > "heading" > "chief" chain, though the standard etymology derives caput from a different root) and the word cop (to cop = to seize, hence a copper/cop = one who seizes) show how the grasping metaphor extends to authority and law enforcement.
Greek káptein (κάπτειν, "to gulp down, to devour") preserves the root with a specifically oral sense — grasping with the mouth — and Old Irish cacht (servant, captive — one who has been seized) provides the Celtic reflex.