I picked up the book today. They're very much like Covenant items from Midnight, but instead of them naturally gaining power, the PC needs to learn about the history of the weapon, and conduct certain rituals or do certain things to awaken the powers.
It's actually very cool in concept. It's a good way to have a campaign where the PCs aren't discarding that old +1 sword like a broken toaster oven when something better comes along. Each item has a story, which is good as it's more reminiscent of earlier versions of the game where magic items were actually special, instead of being a regular commodity, and each one was somewhat unique.
The rituals aren't all about pouring magic oils on it and chanting over a brazier, etc. Sometimes, it's doing something with the item that harkens back to what its original user did with it, or bathing it in a sacred pool for a day, going to the place where the hero who used to own it died and properly interring his bones, and various things like this.
As to the balance/mechanics, I can't really say as I'm still going through the book. But it seems neat, and I'm already thinking of ways to introduce them into the game.
It makes me think a bit of Memory, Sorry, and Thorn, when Simon and a bunch of the servants of Prince Josua were reading through the history of the sword Thorn....where it had been, what had been done with it, and finding that it was more than just an ordinary sword. Then needing to head up north into a dangerous locale to find it, etc. The blade meant something. It was famous not only because of who used it, but what it had been through.
Fully powered, these items of legacy seem like a step between magic items, and artifacts. Unlike those two, often there are negatives to somewhat counteract the benefits the item brings.
Banshee