Oda had crowned King Eadwig in 956, but in late 957 the archbishop joins Edgar, who had been proclaimed king of the Mercians in 957, while Eadwig continues to rule Wessex.
The exact cause of the rupture between the two brothers that led to the division of the previously united kingdom is unknown, but may have resulted from Eadwig's efforts to promote close kinsmen and his wife.
The division is peaceful, and Eadwig continues to call himself "King of the English" in contrast to Edgar's title of "King of the Mercians".
Æthelweard the Chronicler describes himself as the "grandson's grandson" of King Æthelred I. Eadwig is the son of King Edmund the Magnificent, grandson of King Edward the Elder, great-grandson of King Alfred the Great, and therefore great-great-nephew of King Æthelred I. Eadwig and Ælfgifu are therefore third cousins once removed.
Oda in early 958 annuls the marriage of Eadwig and his wife Ælfgifu, who are too closely related.
This act is likely a political move connected to the division between Eadwig and Edgar, as it is unlikely that the close kinship between Eadwig and Ælfgifu had not been known before their marriage.
The annulment of the marriage of Eadwig and Ælfgifu is unusual in that it is against their will, clearly politically motivated by the supporters of Dunstan.
The Church at the time regards any union within seven degrees of consanguinity as incestuous. (This will be reduced to four in 1215.)
At this time, "degree" is reached by counting up to the common ancestor and back: a second cousin would be related within the sixth degree.
Oda is a supporter of Dunstan's monastic reforms and has been a reforming agent in the church along with Cenwald the Bishop of Worcester and Ælfheah the Bishop of Winchester.
He has also built extensively, and re-roofed Canterbury Cathedral after raising the walls higher.
Oda in 948, had taken Saint Wilfrid's relics from Ripon.
Frithegod's verse Life of Wilfrid has a preface that was written by Oda, in which the archbishop claimed that he rescued the relics from Ripon, which he described as "decayed" and "thorn-covered".
He had also acquired the relics of St Ouen, and Frithegod also wrote, at Oda's behest, a verse life of that saint, which has been lost.
He has also been active in reorganizing the diocesan structure of his province, as the sees of Elmham and Lindsey have been reformed during his archbishopric.
The archbishop dies on June 2, 958, and is regarded as a saint, with a feast day of July 4.
Other dates, including June 2 or May 29, are also commemorated.
After his death, legendary tales will ascribe miracles to him, including one where the Eucharist dripped with blood.
Another is the miraculous repair of a sword.
There is no contemporary evidence for veneration being made to Oda, with the first indication of cult coming in the hagiography written by Byrhtferth about Oswald, but no hagiography specifically about Oda will be written until Eadmer sometime between 1093 and 1125 writes the Vita sancti Odonis.
Oda was known by contemporaries as "The Good" and also became known as Severus "The Severe".
