en_tn_condensed/1sa/18/21.md

that the hand of the Philistines may be against him

"so that the Philistines may kill him". Harming someone is spoken of as if it were placing one's hand on that person. Here, Saul is referring to killing David. See 1 Samuel 18:17.

You will be my son-in-law

"You will be the husband of my daughter"