What is the meaning of "Im ha'Even"?
Radak: It is near the rock. The same applies to "Im Be'er Lachai Ro'i" (Bereishis 25:11).
Why does it say "Mido"?
Radak: The Vov is superfluous, like the Vov in "Mido Vad" (Vayikra 6:3). Mido is Samuch to Levusho; Levush is a general term. Mido is a particular garment that was known to them.
Radak citing Targum Yonasan: It is the belt.
Ba'al ha'Turim: It says so here, and also regarding Bigdei Kehunah "Mido Vad" (Vayikra 6:3); they resembled military garments 1 . Also the neck opening of the Me'il was (Shemos 28:32) "k'Fi Sachra", i.e. folded over like armor (Rashi there).
Malbim: It is a special garment that the head general wears. David had not yet deposed Yo'av. Levush always refer to a garment special for something, e.g. "Levush Malchus" (Esther 6:8), "Hotzi Levush l'Chol Ovdei ha'Ba'al" (Melachim II, 10:22).
Nidah 13b: The Michnesayim are like pants of Parashim (soldiers on horses. Rashi brings an alternative text 'Perushim' (pious men).
What is the meaning of "Metzumedes Al Masnav"?
Rashi: It was very close to his body, to the width of his loins, unlike people gird swords, so it will fall easily, and he will not need to remove it from its case.
Radak: It clung to his loins.
Malbim: Some sheaths fit the sword snugly and cling to it. One hangs the sword from his loins, and the sheath does not fall. Some sheaths are wider than the sword; it would fall by itself, so one hangs the sheath from his loins. Here the sheath clung to his loins, and not the sword. When the sheath fell, the sword came out by itself. Amasa did not heed this.
What is "Ta'arah"?
Radak: It is the sword's case.
What is the meaning of "v'Hu Yatza"?
Rashi: He went towards Amasa.
Radak: He left his place, i.e. the big rock or the city Giv'on.
What is the meaning of "va'Tipol"?
Rashi: The sword fell from its case, for it was smooth and polished, and it was not hanging on the side of his thigh, rather, to the width of his loins. He bowed slightly towards the ground, it fell 1 from its case, and he grabbed it in his right 2 hand. Amasa did not notice.
Mishbetzos Zahav citing R. M. D. Wali: Shamayim caused it to fall. Yo'av took this as a sign that (a) His Gevurah will diminish opposite that of Amasa; this aroused his envy. (b) He should avenge the rebel (refer to 19:14:1:2 and the notes there).
Rashi (Melachim I, 2:5): He wore it this way in order that it fall, and Amasa will not realize that he picks it up to kill him.
Kli Yakar: Radak and Mahari say that he grabbed it in his left hand, for Stam "Yad" is the left hand. Also, he held Amasa's beard with his right hand! (verse 9)
