1)
What is "the blood of Beis Sha'ul"?
1.
Radak: Refer to 14:7:1:2.
2.
Radak citing Targum Yonasan: All liability of Beis Sha'ul.
3.
Malbim citing Mahari: Sha'ul and his sons were killed. Hashem should put this on you alone, for you are worse than him in three ways. (a) "Hashem gave your kingship to Avshalom" - unlike you, who took it from Beis Sha'ul by force. (b) "In the hand of Avshalom your son" - Hashem put evil on you from your house. (c) "You are in your evil" - for you are a man of blood, unlike Sha'ul, who did not see the evil in his lifetime.
