The word “This” refers to David’s actions. This implies that if David were to pour out blood needlessly or attempt to avenge himself, he would feel grief and have a troubled heart. But since he will not do those things, he will not feel grief and have a troubled heart. Alternate translation: “Your action will not cause you the grief or the troubled heart that pouring out blood needlessly or trying to avenge yourself would cause you.”
A troubled heart is a metonym for feelings of guilt. Alternate translation: "Your action will not give you sorrow or guilty feelings" or "You will not do something that causes you to regret what you did and to feel guilty" (See: [[rc://en/ta/man/jit/figs-metonymy]])
Pouring out blood is a metonym for killing people. Alternate translation: "that you have killed innocent people" or "that you have killed people needlessly" (See: [[rc://en/ta/man/jit/figs-metonymy]])
Abigail speaks of herself and David as if they are two other people, to show that she respects David. Alternate translation: "you ... you ... yourself ... you ... me" (See: [[rc://en/ta/man/jit/figs-pronouns]])