The first time I heard this term used was in a kids movie...animated. You need to check this film out if you have not seen it. Very good for both children and adults alike.

It is "The Road to Eldorado" starring Kevin Kline (Tulio), Kenneth Brannagh (Miguel) with an excellent sound track written by Elton John and Tim Rice who also did the soundtrack of Lion King...

The quote is from a fight scene in the first 5 minutes of the film starting...where the two con men after having cheated a dice, create a duel scenario to change the topic at hand.
At which point one of them says

Tulio: "Any last words??"
Miguel: I will cut you to ribbons, fool!"
Tulio: "Such mediocrity.! Let your sword do the talking!"
Miguel: "I shall!! It will be loquatious to a fault"

As a result of this my 7 and 9 year old boys understand what it is to be LOQUATIOUS.