One way to hold this word: a single thin, pointed spike. Everything stiletto names has that same outline — a blade as narrow as a long needle, a small tool that pushes a hole through leather, and a shoe heel that meets the floor at a point the size of a fingertip. The word is not telling you what the thing is for. It is telling you the shape.
From the word’s history
The packet's source entry says stiletto was borrowed from Italian stiletto, and analyses it as Latin stilus (a pointed writing tool) plus the Italian ending -etto, which makes things small; it also notes stylet as a doublet. That reading fits the picture above: a small pointed thing.
證據裡的來源說 stiletto 借自義大利文 stiletto，並拆成拉丁文 stilus（尖頭的書寫筆）加上義大利文的小稱字尾 -etto，另外指出它和 stylet 同源。這條線索正好對上上面那個畫面：一個小小的、尖尖的東西。
Wiktionary, "stiletto"
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