Buttler hit 32 off just 10 balls at Edgbaston to help the hosts level the three-match series at 1-1 following Monday's washout at Old Trafford.
"Jos Buttler's was a game-changing innings," Broad told Sky Sports News. "I don't think he needed it because we know how good he is but that's the first time he's done it in international cricket and, going into a World Cup, he's going to be useful for us.
"I've learned we've got a very good squad and I'm excited by the players that we have."
England begin the defence of their T20 World Cup crown against Afghanistan on September 21.