Fire arrows are a pretty common trope, however, according to Lindybeige, they're not really that great. In contrast to fire, what if you make arrows that create an endothermic reaction upon impact, freezing its surroundings.
I have a rough design idea for these: The head of the arrow carries a container with two separated compounds, which mix together upon impact when the container breaks, and start an endothermic reaction. Now onto the question.
There are a few questions I have; what materials should be used in the making of the arrows, including the container and the compounds inside (the compounds should be as reactive as possible)?; and what could they freeze, flesh, blood, armor (what armor materials?)?