ah ok - I did actually visit that room, but didn't see a lever or 'off button' so assumed it just carried on....When I get back there I'll follow that route. Still a pita that' its not just outside...
It's enemies (with very big balls
), not a lever. There are actually 2 sorcerers spawning these balls, guarded by a mad pumpkin and another sorcerer. Once you kill the 2 sorcerers, they don't respawn, and the balls will stop.
To be sure we're talking about the same room: there's a ladder in the room on the left when you enter the hall under the ball source. I think the door needs to be opened from inside, the first time, so you may have to enter the courtyard, go to the left, and jump through the window (I assume you've already defeated the mini-boss in that courtyard). So all you have to do, from the Debate Parlor, is jumping on one of the arcades, jumping on the pavement, then jumping back on one of the arcade pillars when the ball rolls down, and quickly sprinting to the hallway.
PS: Regarding shields, I also remembered one that was awesome but heavy: the Erdtree Greatshield (weight = 13.5). It has a unique skill, Golden Retaliation, that throws sorceries and incantations back at its caster. You only get it a little later in the game, by defeating a specific group of enemies. Strangely, it requires STR=30 and FAI=12, so maybe you'll need a STR+5 talisman or better and a higher level, but it's worth remembering, especially since it's a 100% phy guard shield. You probably remember that shield from the first Tree Sentinel you saw, if you tried to fight him. He doesn't drop it, though; the ones dropping it are
the Tree Sentinel Duo, in the Altus Plateau when you get near the capital. Perks of serving the Erdtree.