He blessed him

King Melchizedek blessed Abram.

Blessed be Abram by God Most High, Creator of heaven and earth

This can be stated in active form. AT: "May God Most High, the Creator of heaven and earth, bless Abram" (See: rc://en/ta/man/translate/figs-activepassive)

This refers to the place where God lives.

"God Most High, because he has given." The phrase starting with "who has given" tells us something more about God Most High.

This is a way of praising God. See how you translated "blessed be" in Genesis 9:26.

"into your control" or "into your power"