In Yu-Gi-Oh! GX, Bastion Misawa states that this card is so powerful that it has been banned from official tournaments, making it one of the few cards that is Forbidden both in the anime and the real-life card game.
Oddly enough, despite this Kaiba uses this card against Zigfried von Schroeder during his Grand Championship, suggesting that either this card was banned after this Duel occurred or that it didn't matter since their Duel wasn't an official match of the tournament.
This card is possibly the rival of "Black Luster Soldier - Envoy of the Beginning", as both appear to be opposites of each other by their theme and appearance (the armor and horns on both their heads). This is further supported by the fact that whilst Seto Kaiba uses this card, Yugi Muto uses "Black Luster Soldier". This sets up a rivalry between the cards, since Yugi and Kaiba are great rivals throughout the story.
Both "Envoy" cards possibly allude to epic poems that tell of heroic knights or warriors fighting against dragons, who were portrayed as powerful but evil creatures in medieval times. An example would be Beowulf when he went to fight against a dragon in his last quest before his death.