Well, I'm not so exact...
I have on my mind the K pronounciation from a Latin-speaker perspective, not from an English-speaker, sorry. Perhaps for you will be more exact de-care-toh, with the R as in Spanish or Italian.
However, it's very frequent to ear the ecclesiastic people spelling de-chair-toh, but this is only due to the Vatican influence, in wich Latin is ever present the Italian language, where C before A, O and U the spelling is similar to K, meanwhile before E and I is similar to CH. In this way a Spanish, Italian or Irish priest can spell:
CIRCVS = CHÍRCUS
CAESAR = CHÉSAR
CIVITAS = CHÍVITAS
CERVVS = CHÉRVUS
In the evolution from the Latin pronounciation to the Romanic languages (as Italian, Spanish, French, Portuguese, etc) there was the next steps:
Classical Latin (from the Romans):
CERVVS (CARE-WOOS)
> CERVU (CARE-WOO)
> CERVU (CARE-VOO)
> CERVO (CARE-VO)
> Proto-Romanic TSERVO
> old Italian CHERVO, old Spanish TZERVO, old French TZERVO
> modern Italian CHERVO, modern Spanish CIERVO (with the same value for C as English TH in THOUSAND, in Spain but not in Latin America or Andalusia) and modern French CERF (with the same value for C as in English, a kind of S).
It's to say, the Italian spelling of CE, CI (CHE, CHEE) is only representative of an old common step in the Romanic languages history, and the modern spelling in Spanish or French is a less conservative one, more evolutioned.
As Italians are the historical genuine descendants of Romans, for centuries the Latin spelling of the Italian people was considered the right spelling, only from a prestigious prejudgement, later denied by the Philology.
Regards
