Sydney enters the 17 May decider in red-hot form after hammering Adelaide United 4-1 in the second semi-final, a day after Victory belted Melbourne City 3-0.
The grand finalists are both chasing a third championship in a repeat of the 2010 grand final.
Five years ago Sydney came out on top and Arnold is confident it is headed for another triumph.
Victory finished the regular season three points clear of the Sky Blues to claim the Premiers' Plate.
But since the resumption of the league in January after the 2015 AFC Asian Cup break Sydney has a slight edge.
Both sides have proven to have incredibly potent attacking stocks but while Victory has scored more goals overall, Sydney has found the back of the net 41 times to Melbourne's 34 and has claimed five more points in the 16 games since January.
With Sydney yet to be beaten on the road, Arnold believes it has nothing to fear.
"We've sent a message that I've been saying since January to today that we're the best team in the league," he said.
"Since the Asian Cup that's 41 goals in 16 games. We're getting better and better.
"That's the belief I have and the stats will show you since Christmas we've got four or five points more than Melbourne Victory.
"We have to go down confident and our away form is outstanding so we'll be extremely confident."
Arnold knows what it takes to win a championship having lifted the trophy with the Central Coast Mariners in 2013 when Victory mentor Kevin Muscat was still playing.
But just one game away from the title, Arnold isn't about to underestimate his counterpart or the task ahead.
"I couldn't be prouder of what we've done but we've won nothing," he said.
"Monday we're back in at work and we've got a hell of a challenge ahead of us to go to AAMI (Park).
"I want them to enjoy the next few days but overall we're close but we haven't achieved anything."
With both Etihad and the MCG unavailable next Sunday due to AFL fixtures, Football Federation Australia has decided to stage the grand final in the much smaller venue of AAMI Park, which has a capacity of 30,000.
For Arnold that's just another plus for his charge.
"The good thing about that is there's only going to be 25,000 people there and not 55,000 so it shouldn't be too daunting down there.
"It will be a nice little crowd."
