Rodolphus simply snorted. "You don't just leave when you want to, Antonin. You of all people should know better than that." He didn't say anything about Voldemort and Potter. For he knew it would happen, and he partly agreed with Antonin's sentiment. The one about The Dark Lord being deluded, that is.
He ignored the jibe about his sword, smirking as he saw Antonin attempt to call in magic that wasn't his to use. Now that was quaint.
He knew his first strike would not hit - he had no intention of making it so. But he did snicker at the overconfidence of the old man, merely deflecting the dual blades with one easy movement. It was so easy to anticipate the dual strike at opposite ends, but rather than let him rest on his laurels, he brought his sword in for a strike, even as Antonin was trying to regain his balance.
Two swords were foolish, and bred overconfidence as he let the dark magic settle around him.