'Able' in the Bible

{And then} one day when Eli was lying in his place (now his eyes had begun [to grow] weak so that he was not able to see)

Now Eli [was] {ninety-eight years old} and his eyes {stayed fixed ahead} and he was not able to see.

Then the men of Beth Shemesh asked, "Who [is] able to stand before Yahweh, this holy God? And to whom shall it go up from us?"

If he [is] able to fight with me and he defeats me, then we will be your servants; but if I prevail over him and defeat him, then you will be our servants and you will serve us."

But Saul said to David, "You will not be able to go against this Philistine to fight with him, because you are [only] a boy, whereas [he has] been a man of war since his childhood!"

Then David strapped on his sword over his fighting attire, but he tried in vain to walk [around], for he was not trained to use [them]. So David said to Saul, "I am not able to walk with these, because I am not trained to use [them]." So David removed them.