The Murder of Aifé
When Cuchulainn went to study weapons in Alba with Scathach and she gave him her daughter Aife and he left her pregnant to return to Ireland, he said to her, “Here is a gold arm-ring for you; and if you beget a son, send him to me in Ireland as soon as his wrist fills the ring. Call him Aife Ainfer and tell him not to reveal his name to anyone alone in Ireland. »
She gave birth to a son and did with him as she was told. She taught him all the feats of arms except the turn of the Gae Bolga, because his father had taken the Gae Bolga with him in Ireland. When Aife Ainfer came to Ireland, the men of Ulster were assembled in Mag Ene. They saw the curach come to them and Munremar was sent to ask him for news; but Ainfer Aife said he would not reveal his name to any single person.
Then a fight ensued between him and Munremar and he put the belt of his sword around Munremar's wrists. So Dubthach was sent there. He did the same to her. Cuchulainn then went down and likewise gave him no information. Both fought, but Cuchulainn could not do anything to him on earth.
“If your skill on the sea is worth that on land,” said Cuchulainn, “your fight is good. "
"It seems to me that my skill is no worse on the sea," he said; and they went out to sea. Cuchulainn was still unable to do anything to him, until he threw him the Gae Bolga and killed him.
“Say your name now,” Cuchulainn said, “since your time has come. "
“I am Ainfer Aife,” he said, “son of Cuchulainn, son of Sualtam. So he [Cuchulainn] took him on his back to where the Ulster men were and there is a testimony of that [namely these verses]:
"Heavy the burden
That I carried through Mag Ene!
The large arms of my son in one hand.
And in the other his remains. "
Cuchulainn was then sued by the men of Ulster; and he was declared a native of Ulster and half of the wergeld was [demanded] of him for his son. Because he had killed him in error and he was an innocent person in the guise of a guilty person, so it was a fight.
This is the reason which justified it, whereas there had been combat: that it was not with the consent of the tribe or the race that it had done it.
Why did Cuchulainn have to pay half awergeld for his son?
Because he was a stranger in Ulster, although he was one of them (?). The measure of a cantred of Murthemne was his own land in Ulster and thus he was [declared] a native and his son a stranger, and the half-wergeld was given to Conchobar.
What made the halfwergeld was given to Conchobar?
It's not difficult. Here is the reason. Cuchulainn was a parricide and the parricide receives neither inheritance nor wergeld. Conchobar was his next of kin and he was [accordingly] given the half-wergeld.
If he had been an Ulate, he would have been an innocent person in the guise of a culprit. If he hadn't been one of them at all, he was a guilty person in his own guise ****** to be given to Conchobar as the price of compensation.