What is the significance of a sharp sword?
Rashi: It is a sign of Nebuchadnetzar's sword.
Radak: All this was in a prophetic vision.
Malbim: This is a sign of what will be at the end of the siege. Yechezkel should take a sword and make a razor from it.
Who are "Galavim"?
Rashi #1: It is a Greek word - shoemakers.
Rashi #2: They sell parchments.
Rashi citing Menachem: They are barbers. There is nothing like this in Torah. Radak - they shave people's heads and beards. The blade it very sharp; it cuts quickly. Bereishis Rabah says that an angel held Megalev 1 . Targum Yerushalmi of "v'Chol Zakan Geru'ah" (Yirmeyah 48:37) is Magliva.
Bereishis Rabah (41:2): When Avimelech took Sarah, the angel said that he will strike him or leave him, as she desires.
What is the significance of shaving his head and beard?
Radak (2): This is a Mashal for Hashchasah (destruction) via a plague, just like a razor is Mashchis hair totally - "v'Lo Sashchis Es Pe'as Zekanecha" (Vayikra 19:27). It says about Hashem's destruction of Machaneh Ashur "Yegale'ach Hashem b'Sa'ar ha'Sechirah" (Yeshayah 7:20).
Malbim: Hair clings to the body. It hints to the nation that Hashem clung them to Him, and now He removes them from Himself. People used to shave the head hair; it was unsightly to have [much hair]. This is a Mashal for Resha'im. Hair of the beard is honorable; it is a Mashal for Tzadikim. The Nimshal is, Tzadik will perish with Rasha.