Nah, it's just the game that doesn't manage its resources well enough, happens to some/most of us.
It's a RAM issue from the game, meaning it reached its maximum of 4gb (being a 32bit application), from poor RAM management. As far as I know, it's easy to trigger by either being in populated channels, like ch.1, or through PVP game modes (like Onslaught, reminds me all those bans from this crash), and, I guess from your case, battles using many different assets like mobs or bosses.
Best way to avoid this error would be to avoid what I said triggers it in the last paragraph, mostly populated channels and PVP. I don't, or very rarely, see that error on my end.
I don't know if it's related or not, but out of the blue today, I have gotten a "Unauthorized program detected. Terminating connection." pop-up that kicked me out of the game in the middle of a Selren raid... I was really scared my account just got banned, but I could log in right after. I didn't run anything more on my PC, so I would assume it is a false flag.
And I always have my usual softwares running (Groove Music, Discord, Firefox, Nexon Launcher, iCUE, antivirus, logitech game assistant, GeForce Experience, Samsung Magician...), which would never provoke that error. And opening anything else like Word/Microsoft Access and other software for work (And nothing related to programming :x ) wouldn't trigger it, otherwise I would close Vindictus to work.
So I suppose it could be related to that BlackCipher's rampage for it to occur randomly like that, and gonna keep playing while I can... Why make such worrying messages tho? :,(
Usually, the level indicated in the stone's name means that it can only enhance equipment of that level (Level 95 = Dullahan gear only), like the +11 to +13 stones/rune there were in the Bravery Shop for lvl 90 gear.
Good thing to point it out too, in case anyone buys it for Astera gear! :x