User blog comment:Blood Reaper/Todd Howard Hinting at Future DLC's and Patches/@comment-770363-20120227200112/@comment-82.54.144.138-20120228185519

Water Arrows = an old feature from a game series called Thief (http://thief.wikia.com/wiki/Water_Arrow) Basically, it's used to put out torches and other fires "remotely" with a bow-and-arrow. The arrow has a fragile tip filled with water in most depictions.