1. The amulet actually speeds up the taint's progress, rather than slowing or reversing it, so it should be handled with care! Additional information about it can probably be handwaved as acquired from Fiona, but essentially it was given to her and other Wardens in a plot by the Architect to accelerate the progression of the taint, leading them to all nearly die, except:
2. Duncan had the blade found in Weisshaupt, which was enchanted in a way that stopped the amulet from working on him. It will also prevent Corypheus' influence from affecting a Warden.
The enchantments on the amulet require blight magic, as cast by darkspawn, so duplicating them would probably be both difficult and sort of controversial, but not completely impossible for a Warden mage with enough research. (Avernus' research could help.) Obviously the amulets are also dangerous, so the real usefulness is probably just the knowledge that Fiona was nearly corrupted beyond saving before she was cured.
The blade can be partially duplicated, but if tested on corrupted samples/animals/etc., it will appear to only counteract the accelerated spread of the taint caused by the amulet. Putting both the blade and the amulet in a cage with a corrupted nug will cause the nug's taint to progress at a normal rate, not to stop entirely, and leaving the blade but not amulet in a cage with a corrupted nug will have no effect. In other words, the blade's enchantments counteract the amulet's enchantments, but don't counteract the Blight itself. The duplicates' ability to prevent Corypheus from influencing Wardens will obviously be difficult to test and confirm, but there wouldn't be any harm in making some amulets or something just in case it does work.
no subject
2. Duncan had the blade found in Weisshaupt, which was enchanted in a way that stopped the amulet from working on him. It will also prevent Corypheus' influence from affecting a Warden.
The enchantments on the amulet require blight magic, as cast by darkspawn, so duplicating them would probably be both difficult and sort of controversial, but not completely impossible for a Warden mage with enough research. (Avernus' research could help.) Obviously the amulets are also dangerous, so the real usefulness is probably just the knowledge that Fiona was nearly corrupted beyond saving before she was cured.
The blade can be partially duplicated, but if tested on corrupted samples/animals/etc., it will appear to only counteract the accelerated spread of the taint caused by the amulet. Putting both the blade and the amulet in a cage with a corrupted nug will cause the nug's taint to progress at a normal rate, not to stop entirely, and leaving the blade but not amulet in a cage with a corrupted nug will have no effect. In other words, the blade's enchantments counteract the amulet's enchantments, but don't counteract the Blight itself. The duplicates' ability to prevent Corypheus from influencing Wardens will obviously be difficult to test and confirm, but there wouldn't be any harm in making some amulets or something just in case it does work.