I've used that word in a sentence thank you!
You and me both buddy.
If it any comfort, I've had to write for a US audience for so many years that I basically can't distinguish now, and my writing is a unholy mix of both.
I just install the US spellchecker and the UK spellchecker and switch accordingly. The Canadian English one accepts both variations, leading to*gasp* literary inconsistencies that academia is not too fond of…
Gygax was his own era's version of nerd (, geek, dork -- whatever term you find most neutral and all-encompassing). Just like a 'very bright young man' from nowadays, he was some mix of part actually bright and using a big vocabulary is just part of the mix with that and part trying to sound smart (exactly what ration one thinks probably depends on one's views of either nerd-dom or Gygax). Overall I think him doing so helped give early D&D a unique flavor that helped sell it to some of the people that found and fell in love with the game. At the same time, I know some kids in my cohort who tried D&D and just kinda bounced off or lost interest quickly or the like, and I think a 'what is up with this?' factor may have been involved.
It also could be spillover from wargames. Vance has been mentioned as an influence on Gygax, but so were any number of games (and history books) focusing on medieval, renaissance, or even Napoleonic eras of war, many of which were written by Europeans, and certainly many of which would have differed to British English for their spelling conventions.
This one might have been so it could serve dual purpose as well -- it is a glamer/glamor/glamour, but it is also the ability which allows you to make your armor more or less glamourous.
So there is no Canadian way? I have a cousin who is real quiet because he grew up in the same house as his exceedingly talkative and forceful dad and older sister. This seems like the same thing.
As a general rule, Canadian English tends to express its unique color in pronunciation and novel words, rather than in local spellings of common words. E.g. Canadians usually use the English "-our" spellings instead of the American "-or" spellings (same with words like "theatre" vs "theater"), but favor our use of "-ize"/"-yze" (analyze, realize) as opposed to the English "-ise"/"-yse" ending. Ironically, I personally prefer the "grey" spelling, even though that's traditionally English. Individual one-off words tend to favor American spelling though: e.g. Canada uses "tire" and "curb" instead of the UK "tyre" and "kerb."
