This is all I found for historical references to [name]Oswin[/name]:
St. [name]Oswin[/name]
[name]King[/name] and martyr, murdered at Gilling, near [name]Richmond[/name], Yorkshire, [name]England[/name], on 20 [name]August[/name], 651, son of [name]Osric[/name], [name]King[/name] of Deira in [name]Britain[/name]. On the murder of his father by Cadwalla in 634, [name]Oswin[/name] still quite young was carried away for safety into Wessex, but returned on the death of his kinsman St. [name]Oswald[/name], in 642, either because Oswy had bestowed upon him Deira, one portion of the Kingdom of Northumbria, himself ruling Bernicia, or, as is more probable, because the people of Deira chose him for king in preference to Oswy. Under his sway of seven years, peace, order, and happiness reigned throughout the kingdom. But in the relations between Oswy and [name]Oswin[/name] there was apparent peace only, the former was employing every subtlety to bring about his rival’s death. At length Oswy declared an open warfare, and [name]Oswin[/name], unable to meet the superior forces of his adversary, disbanded his army, either from worldly prudence ([name]Bede[/name]) or heroic virtue (monk of Tynemouth), and made his way for greater security to Hunwald an eorldoman upon whom he had lately conferred the fief of Gilling. Hunwald promised to conceal him but treacherously betrayed him to Ethelwin, one of Oswy’s officers, and he was murdered. He was buried at Gilling and soon afterwards transferred to Tynemouth, though another account says he was buried at Tynemouth. The anonymous monk of St. Albans, who in the reign of [name]King[/name] [name]Stephen[/name] was resident at Tynemouth, and there wrote the saint’s life, says that his memory was forgotten during the Danish troubles, but in 1065 his burial-place was made known by an apparition to a monk named [name]Edmund[/name], and his relics were translated on 11 [name]March[/name], 1100, and again on 20 [name]August[/name], 1103. At the dissolution of the monasteries under [name]Henry[/name] VIII there was still a shrine containing the body and vestments of St. [name]Oswin[/name]. A portion of his body was preserved as a relic at [name]Durham[/name] (cf. [name]Smith[/name], “[name]Bede[/name]”, III, xiv). Eanfleda, Oswy’s queen, daughter of St. [name]Edwin[/name], prevailed upon him to found in reparation a monastery at Gilling, some remains of which still exist, though it was destroyed by the Danes. [name]Bede[/name] in his “[name]History[/name]” (III, xiv) gives a description of his character and features: “most generous to all men and above all things humble; tall of stature and of graceful bearing, with pleasant manner and engaging address”. There is now preserved in the British Museum ([name]Cotton[/name] manuscript Galba A.5.) a psalter which until the fire of 1731 bore the inscription “Liber Oswini [name]Regis[/name].”
source: CATHOLIC ENCYCLOPEDIA: St. Oswin
I don’t care for it on a girl myself, however you’re not the first person asking about opinions on this name for a modern little girl, so it may trend on the girls side over the next few years. I don’t think it will ever be a top 100 girls name, but it may not be a completely unheard of name for girls.
I think [name]Piper[/name] [name]Elise[/name] is a beautiful name.
