When did Hashem break Pharaoh's arm?
Rashi: This was previously - He handed Pharaoh's army over to Nebuchadnetzar in Yehoyakim's fourth year - "Cheil Pharaoh... Asher Hikah Nebuchadnetzar" (Yirmeyah 46:2).
Radak citing Targum Yonasan: I broke Pharaoh's strength, and it was not healed to be strengthened...
Malbim: In the days of Yehoyachin and Yehoyakim I broke one arm of Pharaoh; was taken from him until Nehar Pras - one arm from his land.
Why does it say "Lo Chubeshah"?
Rashi: From that day [that He broke Pharaoh's arm], "v'Lo Hosif Od Melech Egypt Latzeis me'Artzo Ki Lakach Melech Bavel mi'Nachal Egypt Ad Nehar Pras" (Melachim II, 24:7). Also Yirmeyah prophesized with this metaphor that the wound will not be healed - "Alei Gil'ad u'Kchi Tzari Besulas Bas Egypt la'Shav Hirbeis Refu'os Te'alah Ein Lach" (46:11). Chubeshah is an expression of tying a broken bone.
Malbim: Pharaoh wanted to tie the broken bone and strengthen himself there, but it was not done well. One must cure the break - remove the blood that gathered there and formed a scab. Then he dresses the break with soft covers, and afterwards wraps it strongly. If one ties it without the cure and soft covers, it will not return to be strong for work. I.e. Pharaoh's desire to strengthen himself until the Pras in the days of Yehoyakim, this was improper. His arm remained weak, without strength to fight in war.
What is "Chitul"?
Rashi: It is [dressing a wound with] garments and a bandage, like "v'Hachtel Lo Chutalt" (16:4).
What is the significance of "Lispos be'Charev"?
Rashi: This is strength to fight.
