The Hebrew name Atsel (H682) is a place name and also a personal name. As a place, it appears in Zechariah 14:5, describing a valley near Jerusalem. As a personal name, Azal appears in the genealogy of King Saul in 1 Chronicles 8:37-38 and 9:43-44.
The place Atsel in Zechariah 14 is associated with the eschatological day of the LORD — when God will stand on the Mount of Olives and the mountain will split, creating a valley by which His people escape. The name "reserved" or "noble" is fitting: a place reserved in God's prophetic calendar for the ultimate demonstration of His delivering power on behalf of His people.