On Saturday, Whanganui defeated Horowhenua-Kapiti 29-14 and Manawatu 33-5, while Wellington accounted for Taranaki 36-12 to set up the yesterday's final.
Fielding some big ball-runners, Wellington crossed for five first half tries to virtually seal the outcome with a 31-5 lead, and although Whanganui camped in their 22m for most of the third quarter they were unable to bash through.
Both defences opened up late in the match, with Wellington down to 14 after a sinbinning, for the final score of 48-10.
"[Whanganui] did it the hard way, because of the draw," said Davis.
"Wellington, they only played one game.
"They're at that NPC level, that team also plays RDO [Rugby Development Officer competition] - playing as a unit throughout the season.
"They're a really sharp team. Our boys have done well, but it comes down to depth."
In the other grades, the Wairarapa Bush Colts beat their Manawatu counterparts 31-12.
A young, still developing Whanganui women's team played in the Wahine grade and lost to Wairarapa Bush 27-0 and then heavily to Manawatu.