I may have gotten the spelling of "comeuppance" wrong (this gal doesn't have the 25 lb. version of the dictionary), but I'm curious anyway.

What is the root of this word? It seems to mean the opposite of what it intends. Put-down is more appropriate I think

"Adversity is the whetstone of creativity"

I'm just guessing here, but if something 'comes up' then it may imply that it gets settled i.e. someone gets what they deserved, which until that point had not been even or fair...
I'll clear the way for more qualified answers now .... :-)

I can't BELIEVE it
My SOED-CD came up with come-uppance, hyphenated, and defined it as "one's deserts for misbehaviour"
YES! The definition says desert ... and I was equally surprised to discover they are right about desert....Here I was going along thinking desert was an arid, sandy place and SOED says it is "Deserving, being worthy of reward or punishment" .... etc
And another mnemonic bites the dust ...
wow

Yes, folks, that's the proper spelling of the phrase. In the words of the immortal Yogi Stengel: YCLIU