When affected by the 2nd stage of a Graveknight's Curse, a creature is:
doomed 2, hampered 10, and cannot remove the armor
doomed is a standard condition, but afaik hampered isn't. What does it do?
The hampered condition was part of the playtest for Pathfinder 2e, but wasn't included in the official release. Despite that it did slip into a few places, including the various graveknight entries (mostly just referencing the ability, though it was included in the Book of the Dead's variant).
Here's the description from the playtest:
Hampered
Your Speed is reduced. Hampered is always followed by a number indicating by how many feet the condition reduces your Speed. This condition can’t reduce your Speed below 5 feet. If the condition doesn’t specify which of your movement types it applies to, it applies to all of them. You can have both the accelerated and hampered conditions at the same time, so if you were accelerated 10 and hampered 15, your Speed would be reduced by 5 feet.