Good guide, but i dont like 2 things.. exhaust instead of flash is way too risky, he has no escape ability. You should take flash and smite. Also i'd like to have an infinity edge, a blood thirster or any defensive/offensive item like hexdrinker champs instead of the warmog's or the frozen mallet. Having both breaks the balance between damage and tankyness and having more AD would help to ult/kill those squishies faster and thus minimizing the risk of being focused. Now if you do want to be focused get merc's instead of beserker's.
Just my thoughts, good guide overall. + 1

Why would you max W first?
I like maxing E before W because in early level jungling, you won't have to block many spells and the extra 20% AS from a rank 1 E to a rank 5 E should be covered by your Berserker's Greaves and your AS runes. I don't find the cooldown that important, because I'm not laning against heavy AP casters and I'm not receiving a lot of magic damage.
I play him as an off-tank because I find that when I build him pure AD, I die too easily, especially in late-game.

I play on NA; maybe the EU Fort is level 1.

meant to write congrats for the work :/

what can i say, i play a totally different nocturne, but i need to at least point out some obvious mistakes imo. 1st u should level up w before e, except the AS bonus u will find the cooldown decrease most helpful throughout the game, whilst u have already the fear cc your main damage source should be auto attacking. I would like to note that noc is an as/ad so playing him like an offtank won't be as good but it is a choice nontheless. Gongats on the btw.

P.S Why does your account Fort appears to be level 1 on LoL?