The phrase contains a mystery.

Hashem needs nothing.

Creation adds no perfection to His Essence.

Yet He freely wills relationship in the mode of kingship.

Malchus is therefore the Divine attribute most explicitly oriented toward otherness.

This is exactly why a Chavah Kadmonah light fits Malchus so powerfully.

The whole meaning of the Sefirah presupposes the recipient.

Chochmah can be conceived as wisdom.

But kingship without a kingdom is not manifest kingship.

The other is not incidental to Malchus.

The other is where Malchus appears.

This is perhaps the deepest theological dignity Torah gives relationship.

Hashem remains infinitely complete without us.

Yet He chose a mode of revelation in which our response matters.

Not because we complete His Essence.

Because He desired a kingdom in which finite beings can answer.

The dignity is given, not earned.