Red: The Drakes are not crossing dimensions but will be remaining in the current dimension.
BD: Remember after twenty years that number will dwindle especially if Loki decides to go after them with his full force. And that army would make a nice afternoon snack for the Drakes.
Anyways I will say the Aesir are not going to hand over their weapons to the Agamari (especially when they won't be bringing their high tech weapons to begin with). Commonsense would say thats a bad idea after you blew up the Agamari's homeworld, another bad idea is to trust them to give you decent weapons (for the same reason).
Also keep in mind that the Aesir have hidden for centuries, they are rather adapt at inflitrating "secure" areas and going where they please when they want to.
BTW: Threatening the group, and essentially saying if you don't play along they'll die is a quick way to see your legions destroyed (Remember, in stories heros always face impossible odds and survive). Obviously this isn't the desired result so this confiscating idea is going to need to be reworked. Or done in a different fashion since my impression at this point is that it won't work the way you currently have it planned.