For melee Krieg, I’ve not found it to be viable without STV past the high fifties. You lose too much damage and it takes forever to kill big things, in which case you are going down anyway. I learned a lot from Spunky117’s videos on youtube. I suggest a viewing of a few, especially for the OP levels.
The Roughrider is key because it mitigates STV damage to reasonable levels with it’s damage reduction bonus. It’s essential at the higher OP levels. That OP4 Hide of Terra won’t help, because your health doesn’t scale so you do more self damage with the higher roid rating. Fortunately, you do so much damage with boosted STV, you don’t need a roid shield.
The rest of the gear is pretty optional for melee Krieg. You just need to slag, I like the magic missiles, but delayed bouncing betty’s and other delayed AOE slag grenades are useful because they are still going off in RTB. I saw a video from someone on these forums, might have been Bew, where they used the Slowhand to have the option of taking themselves into RTB mode when you are in that annoying area just above it.
The Sherrif’s badge is quite useful for bosses you can’t reliably melee because it increases the axe chucking rate. If you are spec’d into Hellborn at all, the Bee only works with non elemental guns. At OP8, I use the Bekah and the Bee against bosses like Bunker, but the poor man’s version, the Hammer Buster, or maybe a non elemental Sandhawk would be almost as good.