So I have figured out a way to find where Wintersun places it's five unique items.
Disclaimer: Not following these instruction exactly may break your game, bloat up your save, make your scripts send Auryen to the moon. Even following these instructions may do this.
1. Make a hard save for safekeeping.
2. Open the console and type sqv WSN_DistributeUniqueItems_quest
3. You wil get a bunch of variables. You need the second set: "REF 'WSN_Item1Container". 1-5 for all five items. The number is the Refid the boss chest has in your game.
4. DANGEROUS: Use player.moveto with the Refid from step 3 to zap yourself over to the chest. This can break a lot of stuff. In my testing it zapped me to Potema's Catacomb, breaking that quest probably.
5. Make notes of the locations, and type qqq in the console.
You now know how to find the locations where the items are. Reload the save you made in step 1 and have fun!
Q&A:
Q: Oh my god my item is in an inaccesibble location (Like bloated man's grotto before Hircine quest). Can i just console it in?
A: Probably not. Some areas might be safe, some areas not. Read the disclaimer.