why not just use asterisks you may ask

well raised asterisks are used for footnotes and low asterisks are too small

i considered dotted cross ⁜, which i have used in the past, but font support is bad and it’s a pretty busy glyph

i considered ❇️ but it renders as an emoji these days, and can be quite busy when it doesn’t (as is ❈)

✧ is simple and conveys the sparkle without taking up too much space, and it’s easy to handwrite

for a bit i considered using # but # has a slightly different meaning i think

plus it’s impossible to use on any social media site

an outstanding question is whether i want to duplicate the star for single‐word emphasis like ✧this, or only for ✧multi‐word emphasis✧ (which is the convention i follow with † dagger as a proper name mark, and which i think makes more sense for nonpaired bracketing punctuation)