I had thought about completing the story once I got all of the Rare Blades, but after realizing I'm gonna have to grind until my entire body grinds into pieces, I gave up and went ahead and beat the main story.
One reason for this is that I didn't want to over-level for the main story, so I couldn't just level up and fight the higher Unique monsters that gave high-level Core Crystals. But now that I've beaten the game, I can just go ahead and sleep and level-up.
I do have spoilers, including end-game ones, but to be honest, it's been almost 2 months and it was a worldwide release. I'm not even sure I should care about it.
PS: I'm not going to search each of the characters' localized names one by one while writing this, so I'm going to use the Japanese/Romanized names.
PSS: I'll make a separate post on Rare Blades once I collect all of them...