Benaiah speaks to King David as if he were speaking to someone else to show that he respects King David. Alternate translation: "has been with you, my master the king, so" (See: [[rc://en/ta/man/translate/figs-pronouns]])
The word "throne" is a metonym for either 1) the person who sits on the throne. Alternate translation: "make the one who sits on the throne greater than my master King David" or 2) the kingdom over which the one who sits on the throne rules. Alternate translation: "make his kingdom greater than the kingdom of my master King David" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Benaiah speaks to King David as if he were speaking to someone else to show that he respects King David. Alternate translation: "your throne, my master King David" (See: [[rc://en/ta/man/translate/figs-pronouns]])