Freezing rain itself is not dangerous.
However freezing rain can create dangerous situations such as causing the roads to get icy which can then lead to the roads becoming slippery and causing wrecks.
So in that case the freezing rain can be dangerous because it can cause roads to freeze and ice over and cause a deadly or serious injury wreck.
Freezing rain can also cause power outages when the freezing rain ices over the power lines and that additional weight on the power lines start to sag the power lines and then they can eventually snap and cause the power outage.
Freezing rain can also cause tree branches and tree limbs to crack and break off breaking power lines as well.