Here "hand" refers to power or control. Alternate translation: "I will give the Egyptians over to the control of a severe master" (See: [[rc://en/ta/man/jit/figs-metonymy]])
Yahweh speaks of himself by name to express the certainty of what he is declaring. Translate as in [Isaiah 3:15](../03/15.md). Alternate translation: "this is what the Lord Yahweh of hosts has declared" or "this is what I, the Lord Yahweh of hosts, have declared" (See: [[rc://en/ta/man/jit/figs-123person]])