Whatever it is, it's not going to be a DS9 deep cut. So, no missing Dominion fleet or Pah Wraith or anything; this season is basically a TNG reunion + Trek's Greatest Hits. The writers aren't overthinking this stuff so we shouldn't either. It will either be a TNG related concept, or – in my opinion more likely – an idea original to Picard, either derived from seasons 1 and/or 2, or original to this season.
I was thinking the same. It could be the weapon in Daystrom needs another component in order to function and that component is Jack.
How can Starfleet operate their ships if they haven't even got any pants? And that's how Starfleet brought back the skants. ...I should crosspost this to the thread asking what our hopes for the last scene of the series are, because Picard in a miniskirt is up there.
The weapon is Picard. More specifically, a changeling infiltrator impersonating him on Frontier Day. Maybe they needed his corpse to duplicate him. He’s alluded to his speech a couple of times… perhaps an “alternate” address is being planned by the founders. Wouldn’t that be nice? A very Star Trekkian idea if you ask me. Words matter far more than weapons.