The 22-year-old scored his first Town goal since his £400,000 move from Crystal Palace in June.
Grayson said: “He can be what he wants to be.
“We haven’t seen the best of him yet but he has shown glimpses of what he is capable of.”
Scannell, given the chance of a more attacking role because of injuries to strike duo Jermaine Beckford and James Vaughan, responded to Grayson’s faith with the only goal just before half-time.
Scannell missed a late chance to seal the victory but Grayson said: “He was a constant threat with his power and pace.
“He started the season but then got a hamstring injury and when he came back he wasn’t able to get back in the side.
“We have worked hard with him on his fitness, which was lacking, and we’re also working on his positional play.
“He played really well for the under-21 side against Leicester on Tuesday and that’s what earned him his chance.”
Town returned to winning ways after back-to-back defeats in which they conceded seven goals and Grayson admitted his side were still not at their best.
He said: “We have played better and not won but we needed to get back to winning ways. One bit of quality has won us the game.”
Lee Novak crossed for Scannell’s close range finish two minutes before the break and the goal gave Town a lift after a sluggish first half performance.
Town went close to sealing it but Adam Clayton fired over and then saw his downward header blocked by Dean Gerken’s legs.
The home side’s failure to kill the game off could have cost them but for two vital saves from Alex Smithies.
Smithies denied Sam Baldock with a point blank save and then flung himself full length to push away a header from Stephen McManus deep in stoppage time.
Grayson said: “If our finishing had been more ruthless we wouldn’t have been under the pressure we were in the last 10 minutes.”
The Robins crashed to a fifth straight defeat and face a relegation fight but boss Derek McInnes insisted his side deserved better.
He said: “It was a solid, decent performance but one that’s not got us a result.
“We knew that Huddersfield always start games well at home and it was important we knocked them out of their stride. We were hard working and energetic and stopped their best players.
“We looked very comfortable for the majority of the first half. But Huddersfield scoring on the stroke of half-time changed things.
“They had something to hold on to and we were chasing the game. Sam Baldock had the best chance of the game from two or three yards and on another day that goes in.”
City have yet to keep a clean sheet this term but scoring goals has not been a problem.
“We’ve not been finding goals difficult to come by but they were today,” added McInnes.
“We have not managed to be clinical enough and passed over some good opportunities.
“I have to be honest and say there are a lot of positives to take from this game.
“The players deserve great credit for never giving up and this gives me great encouragement going forward.
“We were far more dogged and limited Huddersfield and I don’t think our goalkeeper had a lot to do.”