What I read was that the armory bonus applies only to fates, kill XP in the open world, and deep dungeons. I have yet to see a like a wiki level source that says otherwise.
Are you certain you read deep dungeons?
The bonus applies to enemies fought in normal dungeons and guildhests.
I have just personally tested with Palace of the Dead - you get no bonuses at all. No armoury bonus, no rested bonus, no boosts from the aetheryte earring or similar items.
I actually looked it up again and, yeah, I'm not 100% right here. The armory bonus isn't as limited as I initially thought, but to be clear, I'm aware that it doesn't apply INSIDE the deep dungeons, but to the XP rewards you get once you get out, which the Armory bonus DOES cover, along with many more things than I initially thought I'd read, including dungeon rewards, which is good. To be honest, I was kinda puzzled when I initially thought the the armory bonus applied to only three things, and I'm glad to be wrong there.
That said, the shorter queues and lack of care about gearing still make deep dungeons great for DPS alt-job leveling... and for tanks that don't want to leap right into the "don't be new" environment of random group dungeon tanking! :)
i just want to be able to run deep dungeons with my trust.