They are firing fluoroantimonic acid arrows....penetrates anything an everything until they run out of velocity. 
A superacid is any acid which has an acidity greater than that of 100% pure sulfuric acid. Sulfuric acid has a Hammett acidity function (H0) of −12. Fluoroantimonic acid, the strongest superacid in the system, is 1016 times stronger than 100% sulfuric acid with a H0 as low as –28. James Bryant Conant coined the term superacid in 1927 to describe acids stronger than mineral acids.