1)
Who gave Shalom to Gid'on?
1.
Radak: The angel did, after ascending (disappearing).
2)
Gid'on feared lest he die. Why did he first get a Brachah of Shalom?
1.
Malbim: Death comes from separation and opposition of the elements [of man, i.e. the soul and body]. When there is Shalom between them, there is no fatality - "Hineni Nosen Lo Es Brisi Shalom" (Bamidbar 25:12). Due to this Shalom, Gid'on's physicality did not stop his Nefesh from being able to see the angel. You will not die because your sins were pardoned - "Shalom Shalom la'Rachok vela'Karov Amar Hashem u'Refasiv" (Yeshayah 57:19).
