The Aztecs didn't call him Montezuma. Nor Moctezuma. They didn't call chocolate "chocolate". Heck, they didn't even call themselves Aztec! Though they were an oral culture, we have an idea of what their language really sounded like. Here's why.
~ Corrections ~
As Rodrigo Chacón comments, the transitive "nicua" is not used alone. Instead, expect to find "nitlacua" (indefinite -tla-) or "niccua" (definite -c-). Here's a better illustration for building the verb: "ni___cua".
~ Are you reading instead of watching? (no spoilers) ~
He's commonly known to English-speakers as Montezuma and Moctezuma in Spanish, but his language is a different story. Travel to Mexico and dig into language history. Look at early colonial writers and grammarians, learn their strengths and limitations, then move onto some surprising old and new evidence.
Along the way, you'll learn what the Aztecs called themselves and their language and how they really said "chocolate". You'll study a bit of their fancy grammar. You'll hear me take a shot at pronouncing the reconstructed form of Montezuma's own name as it would've been pronounced in old Tenochtitlan. You'll see how it took modern linguistics to sort out some of the historical evolution of the language's sounds from classical to modern times. Finally, you'll learn about the dramatic differences between common speech and ritual speech. In the end, you can see how the pronunciation, grammar and style leave us with an understanding of Montezuma that's more complex, but also more beautiful, than if his language were a simple Mexican monolith.