The Spanish hechizo (“spell”; nothing to do with the letters in words, but what a witch casts on you!) comes from the Latin facticius (“made by art”; “artificial” — indeed, that which is artificial is just something not occurring naturally but instead made by art!).
But how did artificial change to mean “spell”? Think about it this way: casting a spell goes against nature — it’s what the wicked, crazy and profoundly unnatural woman does! Think of the three weird sisters in Macbeth, and how they unnaturally stir up all the elements!
From hechizo (more specifically, from it’s Portuguese twin cognate, feitiço), we get the English fetish. How? Well, you have a fetish when the recipient casts a spell on you to become obsessed with the object of your fetish, right? Enough said!
That root facticius turned into hechizo by changing via two common patterns: the initial F in Latin tended to turn into an H as Latin turned into Spanish (compare fig and higo, or fume and humo!) and the ‑ct- tended to change to a ‑ch- (compare noche and noctural; or ocho and octagon). Thus the h‑ch of hechizo maps to the f‑sh of fetish.
The “W” sound is a classic Germanic and Anglo-saxon sound. Harsh, it is.
Interestingly, the Germanic and English words with the w- become the gu- sound as these words evolved into Spanish. Yes, in this case, the Germanic and English words — centuries ago — made its way back into Spanish rather than the more common pattern of vice-versa!
One example: the name William maps to the Spanish name… Guillermo. I first discovered this because I was once in a bookstore in Buenos Aires and there was a book “Enrique IV” by “Guillermo Shakespeare”. I needed about a minute to figure out what was happening (Enrique is Spanish for Henry).
The Spanish correr, “to run” seems completely unrelated to the English horse. Looks can be deceiving.
Correr comes from the Latin for the same, currere. Currere, in turn, comes from the Proto-Indo-European root *kurs, which also means, “to run” — just like horse does! Both have the same common ancestor.
The weird thing is: how did the PIE *kurs turn into horse, they sound so different.
The explanation is that, in the Germanic languages like English, the k- sound turned into the h- sound. But in Spanish, the original k- sound remained, although usually written with a c-.
This explains many parallel words that have c- and h- sounds that map to each other between Spanish and English, like heart/corazon and head/cabeza.
Perejil and its English version parsley sound very different. But they are, actually, etymologically the same word.
They sound different because often the ‑s- and ‑sh- sounds in Spanish turned into the letter ‑j- with the Arabic throat clearing sound as a pronunciation. Thus, the p‑r-j‑l of perejil maps exactly to the p‑r-s‑l of parsley.
The English for eager-to-fight, pugnacious, contains the ‑gn- pattern inside it: a give-away to the pattern that ‑gn- words in Latin turned the ‑gn- into a ‑ñ- in Spanish yet remained the same into English.
Therefore, pugnacious maps perfectly to puñal, the Spanish for… “dagger.” It makes sense that “dagger” and “eager to fight” come from the same root, after all. And that root, in this case, is the Latin pugnare, meaning, “to fight.”