I think what Dumbledore does in this scene is making the glass shards into glass dust, not sand. Like when it hits the shield it turns into smaller pieces. 01:37, October 10, 2011 (UTC)

I agree with this possibility. Andre G. Dias (talk) 20:50, April 8, 2014 (Brazil)

Is it possible this spell be a Shield Charm which dissolved the glass shards and transformed them into glass dust? Andre G. Dias (talk) 20:51, April 8, 2014 (Brazil)