Why did the ass see the angel, but not Bil'am?
Rashi: Hashem gave the ass the ability to see it 1 but not Bil'am, who, because he possesed intelligence, would have gone out of his mind had he seen the destructive angel.
Ramban and R. Bachye: Angels are not physical beings, and are not generally visible to humans and certainly not to animals. Consequently, the ass did not see the angel - it sensed that there was something harmful that caused it to turn aside withour understanding what it was. 2
Why was the angel holding a sword?
Rashi: 'Rasha!', he said to Bil'am, 'You are coming against Yisrael using their weapon - the mouth 1 , so I will threaten you using your weapon - the sword!' 2 In the end, he did indeed fall by the sword. 3
Chizkuni: This was Midah ke'Neged Midah, because in Pasuk 29, Bil'am will say to his ass 'if I had a sword, I would kill you!'
In keeping with Yitzchak's B'rachah to Ya'akov, in Bereishis 27:22 - "ha'Kol Kol Ya'akov.". Sifsei Chachamim - "Shelufah" spells "Shelo Peh" (Yisrael's [weapon] is the mouth).
Mizrachi (citing Bamidbar Rabah 20:13): If not for this reason, why did he need a sword? An angel can kill by blowing (Yeshayah 37:36, 40:24)!
See 31:8.
Why does the Torah not mention what affect this all had on Bil'am's two servants and to the dignitaries of Mo'av?
Ramban (on Pasuk 33) and R. Bachye: Either because they walked ahead of him and did not witness what happened or because they were not destined to see it - as generally happens with people who have Ru?ach ha?Kodesh, where they see but others who are with them don?t. 1
Seforno: Because when Bil'am's ass went into the field, he abandoned them. Consequently, they did not witness the episode with Bil'am and the angel. 2
R. Bachye: Like we find in Daniel 10:7.
Presumably, Hashem arranged that they should not witness the episode with the ass, which would have turned Bil'am into a laughing-stock in their eyes. Refer to 22:30:1:1**. See also Ramban on Pasuk 33, who maintains that the dignitaries witnessed everything, as doe Rashi - Refer also to 22:29:1:1*.
How is it possible that Bil?am, who was an accomplished sorcerer, did not understand from the strange behavior of the ass, that he was going against the wishes of Hashem?
R. Bachye #1: This teaches us the extent of Bil?am?s hatred of Yisrael and of his desire to curse them. 1
R. Bachye #2 (on Pasuk 29): The fact that he did not understand that everything that occurred was from Hashem, to teach him that what he was doing was unacceptable and to induce him to retract, demonstrates his extreme stubbornness and evil nature - due to which he decided to treat the entire episode as if it was perfectly natural and nothing had hapenned
