The loins, as in Ezekiel 29:7, signify the marriage of truth and good. In general, loins signify love, and when referring to the Lord, divine love. They can also signify the interiors of conjugial love. In Isaiah 11:5, they signify people in the divine good of love, and reins signify people in love towards their neighbor.

(Odkazy: Apocalypse Revealed 830)

In general, men are driven by intellect and women by affections, and because of this men in the Bible generally represent knowledge and truth and women generally represent love and the desire for good. This generally carries over into marriage, where the man's growing knowledge and understanding and the woman's desire to be good and useful are a powerful combination. In many cases in the Bible, then, "husband" refers to things of truth and understanding, much as "man" does. Magnificent things can happen in a true marriage, though, when both partners are looking to the Lord. If a husband opens his heart to his wife, it's as though she can implant her loves inside him, transforming his intellectual urges into a love of growing wise. She in turn can grow in her love of that blooming wisdom, and use it for joy in their married life and in their caring for children and others in their life. Many couples, even in heaven, stay in that state -- called "Spiritual" -- growing deeper and deeper to eternity. There is the potential, though, for the couple to be transformed: through the nurturing love of his wife the husband can pass from a love of growing wise to an actual love of wisdom itself, and the wife can be transformed from the love of her husband's wisdom into the wisdom of that love -- the actual expression of the love of the Lord they have built together. In that state -- called "Celestial" -- the husband represents love and the desire for good, and the wife represents truth and knowledge.

830. 19:16 And He has on His garment and on His thigh a name written: "King of kings and Lord of lords." This symbolically means that the Lord teaches in the Word who He is, that He is the Divine truth of Divine wisdom and the Divine goodness of Divine love, thus that He is God of the universe.

The Lord's garment symbolizes the Word in respect to Divine truth, as in no. 825 above. The Lord's thigh symbolizes the Word in respect to Divine goodness. Because thighs and loins symbolize married love, and because that love is the fundamental love of all loves, therefore thighs and loins symbolize the goodness of love. That this is due to its correspondence may be seen in no. 213 above. Therefore, when a thigh is mentioned in reference to the Lord, it symbolizes the Lord in respect to the goodness of love, and here the Word as well in that respect. Having a name written symbolizes the character of the Lord, as in no. 824 above. "King of kings" means the Lord in respect to the Divine truth of His Divine wisdom, and "Lord of lords" means the Lord in respect to the Divine goodness of His Divine love. The Lord's kingdom and His dominion have the same symbolic meaning in places where both are mentioned (see no. 664 above).

[2] Because the Lord is called King of kings and Lord of lords, and this means the Lord in respect to both Divine truth and Divine good, therefore the name is said to have been written on His garment and on His thigh; and the name written on His garment symbolizes the Word in respect to Divine truth, while the name written on His thigh symbolizes the Word in respect to Divine goodness, both being contained in the Word. The Word's Divine truth is found in its spiritual sense, which is intended for angels of the intermediate or second heaven, who possess intelligence stemming from Divine truths; and the Word's Divine goodness is found in its celestial sense, which is intended for angels of the highest or third heaven, who possess wisdom stemming from Divine goods. But this latter sense is deeply hidden, being perceptible only to people who possess love toward the Lord from the Lord.

That the one on the white horse here is the Lord is explicitly said above in the book of Revelation:

These will do battle with the Lamb, but the Lamb will overcome them, for He is Lord of lords and King of kings. (Revelation 17:14)

[3] That a thigh symbolizes the goodness of love, and in reference to the Lord, the Divine goodness of His Divine love, is clear from the following passages in the Word:

Righteousness shall be the girdle of His loins, and truth the girdle of His thighs. (Isaiah 11:5)

...over (the cherubim's) heads was... the appearance of a man (on a throne).... From the appearance of His loins and upward..., and from the appearance of His loins and downward..., (there was) the appearance of fire and of brightness all around. (Ezekiel 1:26-28)

The man on the throne means the Lord. The appearance of fire from His loins upward and downward symbolizes His Divine love, and the brightness all around symbolizes the Divine wisdom emanating from it.

(Daniel saw a man) whose loins were girded with gold of Uphaz. (Daniel 10:5)

The man was an angel having the Lord in him. Gold of Uphaz symbolizes the goodness of love.

The thighs or loins have the same symbolic meaning in Isaiah 5:27, Psalms 45:3, and elsewhere.

Regarding the correspondence of the thighs or loins with married love, which is the fundamental love of all loves, see Arcana Coelestia (The Secrets of Heaven), nos. 5050-5062.