There's not been any discussion on it here, but someone dumped all the Black Throne player cards all over social media. That includes the new Bonded cards.

I've written my thoughts on them here (note that I'm talking more about the nature of the mechanic than the specific cards we've got). Anyone else want to chime in?

I'd put a spoiler warning in the title just to be safe, since we're discussing unreleased, leaked player cards.

With the mechanic as a whole, my thoughts for the two in Before The Black Throne are more or less in line with your own - setup with no inherent benefit for the privilege of using the accompanying events and then needing to draw the cards (at least #2/#3) is the big downside. But, as we've seen in the previews for The Dream-Eaters, the mechanic has a lot more flexibility than that, with the Crystalliser of Dreams instead giving you a huge up-front benefit and then adding a weakness to your deck. It's a very broad design space so analysis of the entire mechanic seems a bit pointless - points that apply to some of the cards will be inapplicable for other cards.

The two in the Before the Black Throne are pretty niche cards, which is fine - the best card designs, in my mind, are cards that have niche appeal and cards that are strong early on but should be replaced later on, as both are nice places to aim for in terms of balance and give a lot of flexibility in card design. I think that Occult Lexicon/Blood Rite is mainly going to be for people with loads of draw power (e.g. Minh) and the "limit 1 per deck" isn't as much of a disadvantage for Seekers if you really like the card, because Seekers can tear through their decks at lightning speed and use No Stone Unturned to tutor out whatever they need; the event itself is just not stellar, but I think it would be a lot better for solo or scenarios with lots of Aloof enemies (testless damage being great). Hallowed Mirror/Soothing Mirror was very unexpected but pretty great. Carolyn might want it, but it's somewhat inefficient, though the extra draw does help offset the action inefficiency, and she also has a lot of competition for the Accessory slot - and it's not good enough to justify Relic Hunter; probably if you did take it on Carolyn you would get rid of it about the time you got Ancient Stone (Minds in Harmony). I think Hallowed Mirror is going to find a place in a lot of Mark Harrigan decks though, since healing is great for him, flexible healing more so, he has the draw power to get it and the events it produces into hand relatively frequently, and he has much less competition for the Accessory slot.

Ultimately, since they're "limit 1 per deck", it's a little safer to throw them into your deck and maybe you get benefit, maybe you don't.