also i can confirm that the Terraria crossover weapon is authentic and almost accurate to the original, as having played Terraria for over 700 hours.

get the weapons guide

Yes, similar to that! Some lore rooms spawn once (like the crossover rooms, you get the blueprint(s) and the room won't appear ever again), but others spawn multiple times. The second kind can either have in-game lore, drop items, money, or food!
On the mini-map, the lore rooms will have a light blue colour.

Lore room as in the book?

@girl. They are all unlocked by interacting with a Lore Room in Prisoners' Quarters (similar to the 1st crossover content)

What about the weapons themselves?

Note: There is a small bug with the Katana ZERO unlock, make sure to not have any "shoots an arrow" affixes, those can hinder the unlock!

The easiest and most fun method of unlocking the outfit is by just going into the Training Room, spawning 7+ Slammers, then letting them spawn 9 birds each and just slashing through all of them!

I will say for slay the spire's Ruby key you can also choose the random categories section of the shops to give it a chance to appear. it can also appear in the food shop for much less than at the weapon and gear merchants

thank you brother