With more time on your hands, you can finally get this thing open.

For the next couple of minutes, you use Strokmier to deftly unwind the magical seals keeping the case locked. With time to observe the case and lock, you realize that the intense arcane pulses could easily overload your gauntlet - you will need to work around them. You carefully time your interactions with the lock to avoid the rhythmic pulses of energy the book releases, twirling rings of magic energy like delicate gears. After a few minutes of intense concentration, the final seal dissipates with a sizzle, finally unlocking the case; unfortunately, doing so also sends a jolt of wild arcane power through your gauntlet.

You jerk your gauntlet away before it is charged further, managing to avert disaster, but the runes inscribed upon the leather have already been warped beyond recognition. With a twinge of dismay, you slide off the gauntlet and pocket it. Hopefully you can get it repaired later, but it is almost certainly too dangerous to use now. It's time to see whether the sacrifice was worth it.

Opening the book you've worked so hard to acquire, you find that most of the pages have been hollowed out to form a compartment - hidden inside is a slender electrum key, adorned with purple gems and a thin chain. The arcane power you sensed before is emanating from this key, albeit more weakly now. The key seems important, and it cost you your only weapon to acquire, so you carefully pocket it. Maybe it'll be useful later...

With the work complete, you begin taking in the strange hallway you just stumbled into.