Preface this with a caveat that I am not a Krieg expert in comparison to some on the forums, and I found soloing the Peak hard with him.
In my own Peak style I usually go down Mania, because Release the Beast is very handy - especially for fights like Dukino’s Mom (if you release after the first shock spit that health gates you you’re usually invulnerable for the rest). I also spec Fuel the Blood and Bombadier, because it does yield a lot more power in dealing with more dangerous enemies; for instance, if you kill a midget and then throw axes at Dukino’s Mom you’ll get a lot of damage out pretty quickly.
This approach also lets me spec Silence the Voices - which makes it inadvisable to do much direct melee (though I’ve found it’s not good to do that anyway because it puts you at risk; cover and distance is best at the Peak!) but you can get weak enemies and then StV will buff your thrown axes.
I enjoy a Hellborn + Bloodlust combo when I’m feeling daring but don’t usually spec it at the Peak - a further reason being that I don’t find Bloodsplosion as useful as it might be. It’s good in some fights but the most dangerous enemies are often isolated - like surveyors - and having some form of health regen beyond a Grog Nozzle (which I do usually use) is often a life-saver. You may be more nimble and better at surviving than I am of course.
Keep in mind that fire isn’t very effective at the Peak - enemies that are usually flesh are just ‘normal’ there so take no extra damage from it - so the Rough Rider may be superior to Flame of the Firehawk. DPUH is Krieg’s gun, but if you are going for Hellborn some elemental weapons, preferably corrosive, will be really useful. They let you get Elemental Empathy in particular which can also be a saviour.
And that skin is hella sexy. I can almost see Krieg walking round Dublin in the annual ‘12 pubs of Christmas’ challenge.