Cerebrum's costume

Who: Cerebrum, Appendix
Where: Various
After waiting for Dr Keto in Keto's office, Cerebrum finally gave up,
spray painted Keto's desk pink, then left. Then came the announcment
from Holly, and Cerebrum realized he had no costume. Well, no
problem, he knew where he could get one quickly.
A short while later
It wasn't a widely known fact, but the JMC Blue Dwarf had a museum on
it. The attendant of the museum, shortly after the ship launched,
realized that nobody actually attended it, and has so far spent ninty-
five percent of his time on the ship in bars. What makes this
different from any other crewmember, I don't know.
But Cerebrum was aware of the museum, and was making use of it.
[Are you sure this is legal?] the Appendix asked him?
"Of course," Cerebrum whispered, as he reached what he was looking
for, "You're allowed to do this."
[Then why are you opening up the case with a blow torch.]
"Uh, the lock's stuck," Cerebrum said as he reached the case, and
took out the blow torch.
[Oh.]
A short while later
Cerebrum arrived at the party, wearing his costume. A suit of full
plate mail, complete with a helmet and body shield. And a very nice,
very sharp broadsword to make sure nobody criticized his costume.