Manhattan District Attorney Alvin Bragg has a new weapon in his fight to prosecute former President Donald Trump for business fraud, said former U.S. Attorney Joyce Vance on MSNBC Thursday: keep his former top accountant off the witness stand for the defense. This comes amid reporting that prosecutors in his office are trying to work out a perjury plea deal for former Trump Organization CFO Allen Weisselberg, a witness in past Trump litigation who has largely remained loyal to the Trump family. “I think [it’s] a very important word of caution that is not inked by any stretch and could absolute…