וַיֵּרָ֥א אֵלָ֖יו מַלְּאַ֣ךְ יְהוָ֑ה וַיֹּ֣אמֶר אֵלָ֔יו יְהוָ֥ה עִמְּךָ֖ גִּבּ֥וֹר הֶחָֽיִל׃
And the angel of the LORD appeared unto him, and said unto him: ‘The LORD is with thee, thou mighty man of valour.’
Rashi on Judges
Adonoy is with you, man of supreme power. Since He infused you with such power.