I would guess that the weapons are slightly higher than card rate, given that no known Stephen Cards have been found (in b4 I'm BTFO), but there's actually a respectable amount of weapons.
That still doesn't make the weapons a great rate, though, lol.
It's likely that the weapons drop at 0.05% ~ 0.1% "card" rate, while the card is the regular 0.02% drop rate.