About Dangerous Symbols
These are not decorative shapes that happen to look serious. ☢ is the international radiation symbol, ☣ the biohazard sign, ⚠ the general warning triangle, and ☠ the mark used on toxic substances. They were designed to be understood by someone who does not speak the local language, and that is exactly why they read so strongly in a name — and why they can read wrong.
☠ Here Is the Text Version
The skull on this page is the bare character U+2620, without the variation selector that requests colour. That makes it a monochrome text glyph which takes the colour and weight of the text around it.
The skull symbols page carries the same code point with the selector attached, so it renders as a colour emoji instead. Same character underneath, different presentation — and the text version is the one more likely to survive a name field that filters emoji.
The Rest Are Colour Emoji
⚠️ ☢️ ☣️ are all built the same way as ☠️: an older text symbol plus U+FE0F. 🚫 ⛔ 🔞 are emoji outright with no text form.
🔞 is worth separating from the group. It is the "no one under eighteen" sign, and unlike the others it makes a statement about content rather than about hazard. Several platforms treat it as an age-restriction marker in their own interfaces, so it is not a neutral decoration.
Borrowed Meaning Comes With the Glyph
Using a hazard pictogram as an ornament is common and works well in a competitive tag, where the tone is understood. It works less well anywhere the surrounding words could be read literally — a warning triangle beside a sincere sentence changes how that sentence lands.
If you want the aggressive look without a regulatory meaning attached, the weapon symbols and the sharper entries in lightning symbols carry tone without carrying a legal definition.