Decisions. decisions. I would assume that the missions given to the ones who choose the sgield are focused on protection, which could mean that they would go up against the Brotherhood, while the ones who choose the blades will have missions based on attack, so they may be sent to help annihilate the Conjurers.

But...

Bellatrix's title suggests that they may be the opposite. This is concerning. Oh well, better flip a coin!