After that, it was very much a nip and tuck affair with both sides posing problems.
It was the Blues who struck next, with scrum half Rhys Downes tapping a penalty from five metres and reaching out for the line. Deacon converted for a 10-7 lead and the Blues, with the wind at their backs, looked well set to kick on and rattle up a healthy half-time advantage.
However, when fullback James Loxton fluffed a clearance kick on his own line, centre Ashley Beck was on hand to cross for a try that Biggar failed to convert.
Leading 12-10 at the interval, the Ospreys themselves fancied their chances of pushing on and taking the game away from a Blues side who had beaten them twice in the regular season. Unfortunately, when the kick off was dropped, the Blues assumed a position of promise and wing Joe Xiberas was sent in at the corner for a 15-12 lead.
Biggar levelled matters with a penalty and in the final quarter and with the conditions worsening, fullback Chris Lewis handed the Ospreys the title when he chipped over Loxton and followed up to cross for a try; Biggar converted again.
It was just about a deserved win for the Ospreys although they had to withstand some heavy Blues pressure in the final ten minutes.
Ospreys U18 Captain, Jack Shaw, lifted the U18 Reebok Regional Championship trophy after a presentation from WRU Group Chief Executive, Roger Lewis.