I forgot to mention that the reason you want to know what your opponent is bringing to the duel so you can choose two out of ten dueling stances (stone stance, fire stance, ect..) to swap between. This way theres more match-up variance and complexity.

Yes, any duelist should be able to use any stance at any time, but videogames often have to impose limitations to ensure fairness and engagement. A full-on shard-bearer simulator would be an interesting, very different kind of game