Geist of Saint Traft is banned as a commander in Duel Commander format, but it may be part of your deck.

Any effects that say that the Angel can't attack (such as that of Propaganda) affect only the declaration of attackers. They won't stop the Angel token from entering the battlefield attacking.

If you create more than one Angel token (most likely due to Doubling Season), both are exiled at end of combat. On the other hand, if something else becomes a copy of the Angel token, the copy isn't exiled.

You choose which player or planeswalker the Angel token is attacking. It doesn't have to be attacking the same player or planeswalker that Geist of Saint Traft is attacking.

Although the Angel is an attacking creature, it was never declared as an attacking creature. This means that abilities that trigger whenever a creature attacks won't trigger when it enters the battlefield attacking.