Eduardo da Silva scored twice, including a thunderous opening goal just eight minutes in, and Denilison added the icing to the cake, as Arsenal beat Sheffield United 3-0 at Bramall Lane this Halloween night.    The win means the Gunners are now in the pot for the quarter-final draw which takes place on Saturday.  Also this Saturday is the “biggest game of the season so far,” as an in-form Manchester United pay a visit to the Grove.