Can't be that one, Doom, the cursed shield is got from an NPC in FF6.
There aren't any rare encounters in FF1 besides Warmech.
As for the tunnel of doom, I haven't...really played Dawn of Souls that much, I just informed my friend to get a Monk.
Which was glorious, because halfway through the game he whined 'Monks suck, why did you tell me to get one', then I asked him what he had equipped.
He told me he had really crap equipment, so I told him exactly what an FF1 monk/black belt should be equipping.
It was a glorious moment.
(If you don't know, FF1 monks should equip...)
Click here to view the secret text
×Nothing. At all. There is absolutely no armor, and no weapons, that increase a monk's power after the very, very early levels. They actually decrease it. Completely unequipped, an original NES FF1 second class black belt/monk at level 50 can destroy the final boss in a single hit.
But yeah, I have no clue what Mrimer's going on about, unless he's trying for some clever shenaniganical chicanery where he's making a point.