Each character has a reason or history behind the way they look, and with this, the way they are built, and the ductus tells us precisely this.
A swash is a "typographical flourish, such as an exaggerated serif, terminal, tail, entry stroke, etc., on a glyph", but what rules should you follow when you draw them, and what is the absolute best spot to place them?
Lettering skills are the underpinning basis enabling you to continue on to designing a whole glyph character set of a custom typeface.
Categorizing typefaces works great for printers and historians. For type designers however categorization is misleading and makes it more difficult to understand the designspace.