Fix for word of power quest bug at Arcwind Point

If you're playing on PC, you can use the console command SetStage FreeFormHighHrothgarA 20 to complete the quest and allow you to take further quest, install the Unofficial Skyrim Patch to prevent such bugs in the future.

If you're not on PC, then you are out of luck, unless you transfer your save to a PC and fix the bug there as described above.

If you have XBox:
Look up Northwind point if your Arcwind wop quest won't complete, get the word there and the quest will finish.