again, not read the books.
are magical items a thing in this world? or cursed? is the knife magical, cursed? or is it just Tom and the taint?
Yes to both. There are various types of magical items and each type has a different name. (I’m probably going to fuck up the names and spellings.) There are items that amplify a users amount of power they can pull in “angrael”, there are items that greatly to vastly amplify it “sa’angrael”. Those are solely made for channelers and amplifying.
There are items that are magical and only serve one very specific function, Ta’angrael. Some can be used by magic users, some can be used by anyone. Some items are used by current people for functions they had no intention of being used for when they were made, the knowledge was lost to time. Some they have no idea what they do. Some people have lost the ability to channel or died by using them wrong. Some are locked away in various places, some are kept by royalty, some are used by armies or aes sedai, etc.
The Oath Rod Moiraine mentioned to Ugwene (and they showed a scene with) is a Ta’angrael. When trainees get to the point of becoming an aes sedai they must swear oaths while holding the rod. It forces them to those oathes. They literally can not lie, use the power as a weapon unless as a defense for their life. They bend the truth like a mother fucker though which is why they showed that scene of her explaining how she was able to fool the white cloaks with false stories. There was enough truth in her stories she could say it. She wouldn’t have been able to say “I have never been to the two rivers” for example. If they try to lie it doesn’t come out at all or they choke on their words or something, I forget.
These items all take whatever shape possible, when they were made. From little gemstones, to tiny statues, to swords, rods, helmets, door frames, massive statues, literally anything. There are also just magically imbued buildings, weapons, bridges that aren’t really magical in a sense that they do anything extra. But they can stay sharp forever, never rot, etc. “This sword was power wrought” means someone did something with the power to enhance it in some way.
Cursed items, yes too. Basically anything from that city they were in, shadar logoth, was cursed. He just happened to take the dagger. Taking the dagger didn’t actually start that mold spread, that happens every night in that town. And it was supposed to be mist, not mold, but whatever. It’s part of the cities curse.
Thom is not a part of the taint or the cursed dagger except being around mat while he has it.
There is a huge pool of power that all magic users touch when they channel it to use magic, a male half and a female half, think of it as a literal liquid pool, split in half. The yin yang symbols you see in the show, on flags, banners, the pool of water when nynaeve soloed the trolloc represents the two halves of the power. White for female, black for male. Anyways, the male half is tainted. It has a layer of taint/curse on top of it, to reach through it to use the pure power underneath the men must go through that taint. Think of it like cursed oil floating on the surface of the water (power). They reach through that nasty shit when they channel and it slowly drives them insane. Thom isn’t a channeler.