Eardley, voted in the PFA League One team of the year last season, impressed a watching Armfield.
He told the Blackpool Gazette: "I liked the young boy at right-back. He is a good prospect and he looked comfortable on the ball.
"He was up against a difficult player in Gary Teale, who has played for Wigan and has Premier League experience. But Teale didn't get the better of him all night. What I liked about Eardley was that he wasn't frightened of getting the ball. He did well."
Meanwhile, the Tangerines are set to sign 21-year-old striker Yannick Boli on a one-year loan deal from French giants Paris Saint-Germain having impressed in a trial spell at Bloomfield Road.