Very sorry to bother you. I've finished the game with all four endings now, and even after three full playthroughs I still can't figure out what the secret behind Catastrophe is. I've tried numerous things and believe I understand the lore of who its original owner was, but I just can't figure out what I'm supposed to do with it. Any hints?
Viewing post in Touhou - Grimoire of The Elemental Castle comments
Hi! Thank you for playing!
All 4 endings? Wow. (Technically there's 5 though. Okay, more like 4 and a half, since Reimu's ending has 2 branches)
So to answer that, it's... kinda complicated. It's been so long I can't even remember where I put Catastrophe in the first place! "orz
Okay, the spear itself is a reference to another game entirely unrelated to Touhou Project, just like many of the stuff in the game are. But if memory serves, if it is the weapon that was hidden in a cave that also has a note of some sort with it, then the whole sequence is a reference to this, which is also why the two are unaffected by the miasma in SDM.
Unfortunately I lost the dev files after my old PC went kaput, so I can't exactly check if this is the correct item or not (short of replaying the game again but like I said I forgot 99% of it already). If it isn't then it's just a throwaway reference I added back then, but since it is part of the ancient weapon type, and each had at least some significant reference or story behind it, I'm pretty sure this is the correct case.
As for how to unlock its power, well... it supposed to slowly ramp up in strength as you keep failing to use it, to the point of one shotting the bosses IIRC, but it might or might not have been bugged... Again, can't really confirm without the raw files.
I'm so so sorry about this! And thank you for playing!