to take firm hold: to grasp something, to hold a person up so they do not fall, or to keep a tight grip on what is valued
The picture behind this word is a hand closing on something and not letting go. From that single image its uses fan out: literally gripping an object, holding another person up so they do not collapse, and clinging to something worth keeping.
Its most common use is holding someone up. When Aaron and Hur held up Moses' tired hands, and when God says "I uphold you with my right hand," the word is about bearing weight so the other one does not sink. The wisdom writers then stretch it to holding on to what is good, whether that is a father's words, wisdom itself, or honor.
Hebrew has more than one word for taking hold. חָזַק leans toward gripping by sheer strength and אָחַז toward seizing or catching, while this word carries the steadier idea of holding firmly and holding up. For the supporting sense it runs closest to סָמַךְ, which pictures leaning on and being propped up. Once, turned on its owner, the grip becomes a trap: the wrongdoer is himself held fast by the ropes of his own sin.