1)
Why does it use the expression "Tarom Yadecha"?
1.
Malbim: They will not need to fight against their tormentors with two hands. It will suffice to raise one hand against them.
2)
Why does it mention "Tzarecha" and "Oyvecha"?
1.
Malbim: A Tzar afflicts in deed, and fights. The Oyev seeks his evil, but does not afflict in deed. Raise your hand against the former, and the latter will be cut off automatically.
