Well, hello there sweetie, fancy meeting you here. 
As it happens, my first (and highest) char is also a cold based S&B blademaster. I’m cruising my way through Elite atm. I finished base+AoM+FG because I wanted to explore.
With respect to that build, the best thing that I can do for you is point you to this guide/build.
I have to warn you:
- More experienced players than myself say the build is not , erm, shall we say, optimal. Maybe it’s not even good. But I wanted to play a cold focused S&B char and this was the best that I could find.
- The build, at least in my experience, is very safe and tanky. Since it’s my first char, I am playing completely self-found, and I have no issues with it.
- I died 5 or 6 times because i, and I assume that is the same in your case, had no idea what bosses did and as such I stood in s@&t I should have moved out of. Or because I was soo sleepy at 2 a.m. but really wanted to kill that boss. I blinked and when I opened my eyes it was 15 minutes later and my char was dead. But we will not be talking about those 2 particular deaths now, will we? No, no we won’t!
- Because we are disregarding some powerful dw skills in the nightblade tree, we will have to get some dmg from somewhere else. Since we are kinda limited (according to the guide, ofc) we will switch our focus from flat cold to the cold dot: frostburn. They do go hand in hand, most of the time, frostburn should be your focus.
- Since we are tanky from skills, check the devotion path in the guide, which also focuses on frostburn and tankiness.
- Not too many active skills, at least for me, but might be more than you want, because it also has Blitz. That + the mobility glyph, gives you 2 more buttons to push.
Conclusion: even if it’s not the best build, I really enjoy it. I find it suits my needs atm. I shall see how it fares in ultimate, but for the moment it’s great. 3 mobility skills, safety in Overguard, Blade Barrier, Menhirs Will and some devotions. Can tank most things, and what I can’t tank I can always dot and run around a few seconds before I shadow strike back in.
If you need more info (acquired through first hand gameplay) let me know. Also read the link that I gave you, all of it. It has a skill breakdown and a devotion breakdown as well as some other pieces of advice from other people that played this build in HC.
Cheers.