Abishai speaks as if the enemy were a small object that God had put into David's hand. The word "hand" is a metonym for the power the hand can wield. AT: "God has given you complete control over your enemy" (See: [[rc://en/ta/man/translate/figs-metonymy]])
# pin him to the ground with the spear
This is a metonym that refers to "kill with a spear" (See: [[rc://en/ta/man/translate/figs-metonymy]])
# I will not strike him a second time
"I will kill him the first time I strike him" or "I will not need to strike him a second time"