That build looks totally fine to me. StV is very much a matter of taste. Try it, see if you like it, if you do keep using it, if you don’t never use it again. I’m firmly in the latter category.
Probably wait on Thrill of the Kill until you have Bloodsplosion, since that’s the main interaction with that skill (at least the way I play Krieg). As others have mentioned, life will get much nicer at level 57 when you have both capstones. Your opinion on StV will dictate which tree you favor. My Krieg has only one point more in Mania than you do (Thrill of the Kill) but nearly the entire Bloodlust tree.
For immediate plans, I strongly urge you to go start the Hammerlock DLC and get yourself a Rough Rider. That is by far the best shield for non-Hellborn Kriegs, and should be your top priority.
Also, farm Fastballs if you haven’t already. It’s crazy-good on Krieg, and why I’d recommend the Slagga for slagging instead of the low level bouncing betty others have mentioned (note also that once you have a point or two in Blood Twitch, Krieg will have very good swap speed much of the time). Get used to the interaction between Fuel the Blood and Blood Bath as well. Melee a weak enemy to proc FtB, then Fastball your main target for crazy damage (this is Krieg’s method for one-shotting BNK3R, for example). After getting an explosive kill, try to get good shots off with your guns to benefit from Blood Bath. I’ve had a single Hornet burst take down a full-strength Buzzard that way, which was extremely satisfying considering how annoying he finds Buzzards. A Rapier (level irrelevant - mine is level 30 and my OP1 Krieg is totally fine with that) can help with the FtB procs, but isn’t required.
Otherwise, keep in mind that the scaling of UVHM means you can farm gear. Whenever you need a good corrosive pistol, go visit Knuckledragger for a Hornet. Ditto for Boll/Fastball, Lee/Harold, Bulwark/Rough Rider, Tector/Slagga (after you’ve unlocked it; as others mentioned a level 50 Slagga is fine for painting things purple), and any other items you like.
As khimerakiller pointed out, the Leg. Psycho is a bad COM. As far as I’m aware its only use is for niche builds based around Tediore chucking. I still use a Blister on my OP1 Krieg, but I think I was using a Crunch in the low 50s because I hadn’t found a good Blister yet. Either one is really good, though. (I might use a Leg. Reaper if I had one, but my Krieg spent all of July farming for one with no success, so I gave up… Not clear that it’s actually better than Blister/Crunch anyway. Krieg’s legendary COMs are not the greatest.)
Bosses - definitely try to bloodsplode BNK3R. Even a botched attempt like mine was will take off 50-60% of its health and bring a big smile to your face. As you’ve observed, many bosses are not meleeable or are impractical to melee. Wilhelm was not memorable at all, sorry. Pretty sure I did that under 57, so no Bloodsplosion; probably just used the Hornet and axe-chucking.
Constructors were troublesome. That’s when I tried StV on the advice of the forums here, but I hated it and reverted to a non-StV build. Might have switched to a Bloodsplosion build and gotten RtB again at 57? I forget. Some combination of a Bloodsplosion (using a corrosive Fastball, ideally) off of the turret it tosses in front of it, and/or Blood Bath Hornet bursts to the eye tend to work well.
Note that there’s no need to visit the Warrior in UVHM. If you want to, great, but I only bothered on one of my characters, the others stopped doing story quests in Eridium Blight (to avoid Sawtooth Cauldron) or Arid Nexus (setting up Lady Fist farming for later).