I've gotten the word from Arcwind (had to complete quest via console), and the word from Northwind Summit. Arngeir pointed me toward Arcwind point again, so I completed the quest via console. But... he keeps giving me the Arcwind quest over and over. :(
Hi, guys! This is not a real bug ... is more like a misspelling words ... you have to go to find the word in Northwind not in Arcwind. So, the real name of the quest it should contains Northwind instead of Arcwind.