We already have the same: !!!. Your icon can be used, but color should be changed to Red. Everything relates to Trust should be displayed in Red, and we all are familiar with such color, that is a good indicator of Trust issues.
My suggestion was not about replacing the "
!!!", I think that one is visible enough.
I want to replace the "#" (non-scam guest/newbie warning) with something more prominent. It should not be red, but rather yellow-ish to be consistent with the color of the warning box itself.
redsn0w's icons could be used for both (replace "#" with the yellow one, and "
!!!" with the red one), or perhaps the "#" should be replaced with yellow "
!!!" to make it consistent, but the exclamation signs don't look well in that color.