A) The log is, like other logs, a finite thing. It has the gear pre-selected that you can add to it so you can collect it like you do crafting or fishing. You can "Try On" from the log. It's basically a wearable item repository. Maybe even have it tell you the location of the item. Especially as patches change and it gets harder to figure out where they stuck old gear...

B) The gear is limited to pieces which are Unique/Untradeable. This would limit the size of the log and also restrict its use to pieces that take extra effort to recover, ie. tome pieces or dungeon / raid drops.

C) The gear is consumed once logged. This is optional, but I feel makes sense in a way. The most you lose is the ability to desynth and/or turn in for GC seals. Any piece that you plan to do either of those two things with is obviously not so rare or desirable as a glamour, so consuming the piece should not really impact you.