This question is used to show that the men had committed an especially serious crime. It can be translated as a statement. Alternate translation: "You are even more guilty! It is my duty to require his blood from your hand and to remove you from the earth." (See: [[rc://en/ta/man/translate/figs-rquestion]])
The phrase "his blood" represents the life of Ishbosheth. Here "from your hand" represents Rechab and Baanah, the sons of Rimmon the Beerothite, introduced in [2 Samuel 4:5](./05.md). Alternate translation: "hold you responsible for the death of Ishbosheth" (See: [[rc://en/ta/man/translate/figs-metonymy]])