The phial itself has 5 charges and can be placed anywhere, it's not limited to the Master's Glaive area or even Darkshore. It's kind of an odd ""prop"" style of item that doesn't really look like anything else, so if you don't complete the quest you can keep coming back and getting another item with 5 more charges. No functional use whatsoever, but you may get some funny looks if you lay one down in Dalaran and start offering to tell people's fortunes.