Glitch or smart tactic?

I watched Logdotzip's Greed video in which he talks about losing at the duel arena. He mentions his opponent used the Excalibur "glitch" to heal up. I'm thinking this "glitch" is activating the special before going into a duel and it heals you while fighting. Is it really a "glitch" or a smart tactic? To me, it's just playing smart.