The Mariners coach says the minor premiership "means everything", and was dismayed the trophy was not presented to his team in Wellington
The Mariners' 2-1 victory in Wellington meant the trophy would be heading to Gosford, ensuring Brisbane Roar had no chance of claiming it themselves were they to beat Gold United a few hours later.
But there was no trophy presented to the Mariners after the match, drawing the ire of Arnold.
"I'll probably get called a whinger, but that's disappointing," Arnold said.
"I don't care where you play [the match]. The boys have worked their a---- off for 27 weeks, plus pre-season, and it's not here.
"It would have been nice if it was here. I don't know when they are going to give it to us now."
Having led the league by as many as 10 points earlier in the campaign before suffering a form slump, Arnold revealed his belief that the club's AFC Champions League campaign had "played us back into form".
He also spoke of the importance of claiming the Premiers Plate, clinching a spot in the 2013 Asian Champions League as a consequence.
"It means everything," Arnold said. "I'm old-fashioned in that I think the premiership is more important than the grand final because it rewards consistency.
"It rewards the best team. We're the only team that's gone two seasons and compiled more than 50 points (each campaign). I couldn't be prouder of the players."