Mostly useless skills you can't believe you learned.

[cmacq]

.
I can make nigh perfect (an occasionally compose rather good) music; read and write in four different alphabets; foretell what the professor will say at the Classical Greek and Latin classes; seamlessly translate English text in a few minutes half asleep; make good company etc. etc. All of the above are useless skills; I can't make enough money and whenever I want to pick a girl she prefers to be good friends -on each and every instant in my ~20 years of adult life- and goes after a total or semi-jerk -in more than half of the occasions.
.

You...
my well-adjusted friend, are too bloody Civilized. As the barbarous Kelt are wont to say; Return to your Wild and there you’ll find Her Derde Deva.

Cryptic ambiguity, another mostly useless skill?

CmacQ

[Mouzafphaerre]

.

You...
my well-adjusted friend, are too bloody Civilized. As the barbarous Kelt are wont to say; Return to your Wild and there you’ll find Her Derde Deva.

Cryptic ambiguity, another mostly useless skill?

CmacQ

Dear sir;

Ne Ararsan Bulunur Derde Devâdan Gayrı



Command of classical poetry, yet another useless skill.
.

[cmacq]

Aye, remedy the chase with the hurly burly done, 'Cry Havoc' and let slip the Dogs of War.

Recital of Spear-Shaker, most defiantly a useless half-skill.

[Gregoshi]

Alas, I have no useless skills (that I've learned). In fact, "skill" is a word I find difficult to apply to myself at any level.

Hmmm, maybe that is
a skill in itself...

[Ramses II CP]

VMS version 2&3 commands for automated picker machines. This wouldn't be useless if I'd learned it in the 80s, but I learned it in 1998, about fifteen years after it went out of date, just because I worked with a guy who happened to keep some of the machines around for fun.