I think the answer is in the description, "the Fallen House of Winter are raising a powerful Archon, stolen from the Prison of Elders in the Reef. Find the Archon [u][b]before they fully restore his soul[/b][/u]." I think it would be safe to assume that the fallen that rescued Aksor have already opened his cell, suited and armed him, and let him recover while still in the cell probably providing him Ether (the white crap that flies out of them when you headshot them, and crap you collect on patrol) to recover. Think of it this way, you are not letting him out of his cell, he gets out himself because it's already unlocked and he has regained enough strength to fight. Edit: Also keep in mind at the beginning of the strike, your Ghost comments that because the vex are already there, the Fallen will be prepared. I don't think it's out of the question that Aksor was already freed and armed to begin with, only he is in a weakened state. Edit 2: I like some of the theories below that Aksor was "frozen" prior to being placed in the cell, possibly as a non-lethal way of capturing someone, and then placed in the cell. the "defrosting" process has just completed as you approach the cell. Edit 3: Another good point brought up the debunks part of my idea is that if you do not approach the cell right away, it says "Release" Aksor... I think I'm lost again. Edit 4: So from what I'm seeing, it does make more sense that we are the ones releasing him when we get there (only basing this off the mission text that appears), but the previous theory still holds true about him not being at full strength, likely was armed for battle once the Fallen realized the Vex were attacking, and that he is still recuperating in the cell. I suppose my next question is why do we release him? Is killing him at the point seemingly the only way to deal with the situation?