Albert Barnes on Luke 22:43

Strengthening him. His human nature, to sustain the great burden that was upon his soul. Some have supposed from this that he was not divine as well as human; for if he was God, how could an angel give any strength or comfort? and why did not the divine nature alone sustain the human? But the fact that he was divine does not affect the case at all. It might be asked with the same propriety, If he was, as all admit, the friend of God, and beloved of God, and holy, why, if he was a mere man, did not God sustain him alone, without an angel's intervening ? But the objection in neither case would have any force. The man, Christ Jesus, was suffering. His human nature was in agony, and it is the manner of God to sustain the afflicted by the intervention of others; nor was there any more unfitness in sustaining the human nature of his Son in this manner than any other sufferer.

(a) "angel" Mt 4:11