After running Lord Zyr non stop for a while… I finally got 2 Fractured Winterglass to drop! Yeah! 
One is 925 item power, the other is 917.
Now the funny and puzzling thing…
The item power 917 amulet, got all affixed equal or better than the 925… How come?! 
Anyway, glad I paid attention, gotta use the 917 item power amulet! 
Theres no correlation between item lvl and affix quality. Ive found 2 trip affix boosted items, and they were weapons under 820.
Can I get one of those from you? still havent found one and im already 100=(
haha sure… PM me…
Won’t be playing much Saturday during the (Asutralian QLD) day… but I should be here in the evening (and a little bit in the morning) and Sunday all day!
How do you PM here? whats ur tag ill friend you ingame
Hmm… it used to be that you could see the battle tag here…
Oh well… I guess it’s pat of their on going social effort to remove way of communication! Worked that way in Ow2! 
Anyway, Lloyd#1199 is my battle tag, be online a15 minute, then homeowner come some house work… then maybe 1 hour more after that…
EDIT
the owner is there… so will be AFK…
in fact he just arrived…
Im keeping all my extra winterglasses and I give them to ppl when I farm zir again and they are so happy. I makes my day. I currently have a 50 / 70% one Im using and its insane (i stack attack speed including esu fire keystone and aspect) but I lowrolled the bonus to conjure mastery which is sad. Not sure If I want to masterwork it yet but I guess I should. I can use a momentum potion and clear 70s as fast as I move while carrying one more person. Its just bonkers and this is the nerfed version compared to PTR! 
Its going to be endless farming this which is blizzard stroke of genius as to get a perfect one you need to hit greater affixes and 50/70% so never going to happen for years
hahah i no longer do this when i found out bad winterglass sell for 30m yikes…im greedy AF for now. Will give away when Im rich.
Did you get both the 925 and 917 winterglass from regular Zyr or tormented?
It drops from regular Zir, but it seems more rare than some of the other drops. I’ve ran about 50-60 Zirs this season and the Fractured Winterglass has dropped once. Meanwhile you’ll get 5 million copies of Penitent Greaves and Iceheart Brais.
I was more concerned with the item power they drop at from non tormented Zyr when you’re level 100.
Level 925 gear drops from level 95+ monsters I believe…
The regular bosses like Beast in Ice, Zir, Varshan, Grigoire… are like level 80 I think.
I think Duriel and Andariel are exceptions and always drop 925 gear.
In answer to your question: regular Zyr, both
It doesn’t really matter… The closer to level 100 you are, the more item power level 925 is the only drop
Item power for this mostly affects the resist all it has.