What is the meaning of "Im Lo Yashuv"?
Rashi: If the Rasha will not repent.
Radak (12): This is like Ki Lo Yashuv (Hashem is angry because the Rasha does not repent). This is like "v'Im Yihyeh ha'Yovel" (Bamidbar 36:4) - it means Ki or Ka'asher Yihyeh ha'Yovel.
Malbim: Above (verse 8), David said that Hashem should return (cease punishing David). Also the Rasha should cease! If he will not
Who sharpens his sword and draws his bow?
Rashi: [If the Rasha will not repent,] Hashem [prepares to kill him].
Radak: The Rasha does, to try to kill me. I.e. I am very prone to die, as if his bow is drawn.
Malbim: [If the Rasha will not cease trying to kill me,] he prepares them [for his own doom, like verse 14 says].