Is vitivation a real word?

[sweetidealism]

I think "vitiation" may be the intended word. To vitiate is to make something defective or faulty. Vitivate, meanwhile, doesn't appear anywhere in my dictionary.

[Kensagaku]

At times SE has some weird words thrown in there, and they're not always logical. Though you did make me look through the various sets out of curiosity after that, and I found that a lot of them do make pretty good sense.

WAR - Agoge, after a rigorous Spartan training regimen
MNK - Hescyhast, after Hesychasm, which is a tradition of prayer. Works with the idea of monks rather than just our punchy-version.
WHM - Piety, pious healers? Yeah this one was easy.
BLM - Archmage, again, not a hard one to decipher.
RDM - Vitivation, maybe something like making it more vivid, brighter etc? Could refer to the enhancing side. Weird though.
THF - Plunderer, another easy one.
PLD - Caballarius, Latin for a cavalier; an armored knight, perhaps?
DRK - Fallen, yeah... not hard.
BST - Ankusa, surprisingly that's what they call the elephant goads in Sanskrit. Makes sense, tames an animal.
BRD - Bihu, apparently is a name for a series of cultural festivals as well as some kind of dance.
RNG - Arcadian, refers to being at peace with nature in a pastoral way. Rangers should be close to their environment, perhaps?
SAM - Sakonji, this one was a bit weird; the only reference I could find was a naval officer whose father was a samurai. Perhaps some form of homage?
NIN - Mochizuki, couldn't find a direct reference since it was buried in all the articles about the guy who created bitcoins. Maybe another homage?
DRG - Pteroslaver, the various roots for it make sense, but why are we enslaving our wyverns? What happened to the dragon we raised from an egg?
SMN - Glyphic, after symbols with various meanings. Often you'll see glyphs referred to with magic and such in games and books.
BLU - Luhlaza, drawing a blank on this one.
COR - Lanun, apparently after a seafaring folk whose loyalty is to its captain. Fitting!
PUP - Pitre, no idea on this one, perhaps after an art style or something?
DNC - Horos, means "Dance" in the Greek language. Need I say more?
SCH - Pedagogy, using a dictionary definition because it's fitting, "the method and practice of teaching, esp. as an academic subject or theoretical concept."
GEO - Bagua, a series of trigrams used in Taoist cosmology to represent the principles of reality. We have heaven, marsh/lake, fire, thunder, water, wind, mountain, and earth. So a connection to nature. Works for me!
RUN - Futhark, apparently the name for various runic alphabets. Runic, runes? Good connection.

So the only ones I'm vague on here are RDM, NIN, BLU, and PUP. SAM is sorta weird too.

[Shadax]

Luhlaza is the Xhosa (South African dialect) word for blue or green. Not sure why they only have one word for two colors, but a BLU's SA is "Azure Lore"... azure being the color between true blue and cyan or blue-green.

Mochizuki is named after the 16th century woman believed to have created an all-female group of ninja.

Pitre is French for jester or clown - a usual theme for PUP.

Sakonji was the name of a group of samurai armorers.

As far as RDM, I'm forced to agree with the OP on this one. "Vitivation" is not a real word while "Vitiation" makes much more sense considering it's a RDM's job to make monsters "faulty".