In the story, Horus allows Set to ejaculate inside him, and Set sees this as a victory, that he's dominated Horus. But as Horus now has Set's semen, he gains magical power over Set, allowing him to defeat him.
(I don't know how many other versions of this tale there are though.)
Did Egyptians, like Romans, see a man who ejaculated inside another as dominant, while the receiver was defeated? Did the idea about gaining magical power over someone by taking their semen inside you apply to women as well? Etc.
Just yesterday I attended a lecture by Dr. Uros Matic from Austrian Archeology Institute on Gender related to war in Ancient Egypt. You do have several female pharaohs smiting - but if you look close enough, they are always dominating female captives. The only time that this is different was Hatshepsut as a Sphinx dominating male captives, but this was during her "male" period at the end of her reign. He didn't talk about semen by name, but when you are talking gender, that is all a part of it, right? Gender understands violence and who has the physically dominates - the Ancient Egyptians used gender to femininize the enemy. In the Middle Kingdom there is a Stela by King Senwosret lll at Semna that had the text that translated his enemies were not man enough and they retreated with limp phalluses. They had their back to him which was a play on the sexual position of the men. A stela of Usersatet, Viceroy of Kush under Amenhotep ll, showed his enemies not as men but men with the female determinant after there names, basically calling them women. Merneptah, Rameses ll son and successor, had a stela made that called the 9 enemies of Egypt were like the women of the royal harem. All this using females terms to undermine the enemy as women were seen as weak and needed protection. At Medinet Habu, there is a battle scene with Ramseses lll fighting the Libyans and they all were naked and had limp penises - gods like Min, Min-Re all have hard penises - they are all powerful. A limp penis being women like, it was useless and unpowerful. The 25th dynasty King Piye had text on one of his temples that read that those he conquered had legs like women and he made the bulls into women. King Intef of the 11th dynasty had a register in one of his temples that the Egyptians pulling the hair of the Asiatics, a submissive post, what man would allow another man to pull his hair? That is a feminine act! In the New Kingdom, you have Rameses ll Temple in Beit el Wali South that show Nubian soldiers running away, not even trying to fight, running with their backs to the king - against that sexual connotation. If you look very closely at the Narmer palette, you will see the headless men - ah, but have you noticed that one, and only one, has a limp penis? They all have their heads between their legs and they all but one have their penises on their heads, some think the penises are in their mouths. That is for another discussion. We have the famous tale of Two Brothers. In the tale, one is married and the younger brother lives with them. One day the married brother is away and his wife tries to seduce the younger brother but he does not accept her advances. Her husband comes home and the younger brother is not home yet, and the wife tells her husband that she was raped by the younger brother. The husband is so mad that he finds his brother and cuts off his penis. Eventually the younger brother does marry a woman. At the end of the story, he tells her not to go outside, the he can not protect her, because he is a "woman" - he has lost his manhood and masculinity. He has no power. So, you see, there are a lot of hints, big and small, about sexuality and power (sorry, no semen) but kings from the 5th dynasty onward did attempt to feminize the enemies - they are passive and weak and it is the Male that is dominant and will win. You see the smiting scenes on most every pylon in Egypt. The King has the divine male power and he is shown bigger than everyone in the scene, the Egyptian soldiers are smaller than him but even smaller are the enemies they are smiting and fighting. Now, we do have scenes where it looks like they are counting war trophies - some are hands and some are penises....what is the difference? Why not all hands or all penises? The answer relates to (on the temple scenes with Merneptah and Rameses lll) and it is difficult to say this but the reason the good doctor thinks is that they represent different ethic groups. The Libyans got their penises all cut off! Now, why pick on the Libyans? Well, during this period of time, the Nubians really were that powerful and Egypt needed their gold. The true enemy that had power and could (hopefully not) beat the Egyptians were the Libyans - so the kings had to make them appears as "limp" and beatable as possible - and how to do that, cut off their penises. Pile them up. They are war trophies. Some also think they did not take the whole penis but the uncircumcised foreskin. That is another debate. And there was one last question to the professor before we all said good night - What about the asexual colossus of Akhenaten (Amenhotep lv)? Without a penis, did that mean he was weak - Absolutely not. He did not have a penis to take - he was portrayed without one so he had all his power, no one took his power, no one cut his penis off (and we can debate that the colossus represented both male and female) but the bottom line, so to speak, is that he had his sexuality the way he wanted it so he had power. Oh! One more thing, the enemies that had their hands cut off, well they were not Egyptian so they would not go to the afterlife anyway, but, whatever afterlife they went too, they could not regenerate because they could not masturbate and spread their seed - so, finally, some talk of semen! Hope this kinda helps!