Slash n' Dash Rafa - Full Green Tree Melee Build - UVH5

Gear

Class Mods
Esgrimidor
Additional melee crit chance as well has letting us extend our action skill duration with those crits. Very good unique effect as is, but it's also able to roll up to 5 more points into Cruel Accrual, giving us up to 200% skill damage from it. This is an incredibly effective class mod for mobbing as well as still having good potential for bossing. Unfortunately, this class mod can also roll points into Booming Business. Ideally you don't want that, but if it happens to roll on a mod that's incredible otherwise, you can use a non-splash ordnance.

Buster
Buster is for when you really want to up your bossing potential. The unique effect is useless to us however the ability to roll up to 5 points into Per My Last is not. This gives us a 25% chance for our action skill damage to deal double, which lets Groundbreaker start to snowball insanely fast. In the video you can see boss kills using a Buster that only has 3 points into Per My Last and those only get better with more.

Repkits
Triple Bypass
This is the Repkit I use most often due to the amazing synergy it has with Now With Caffeine. This Specialization directly cuts away 25% of your cooldown, meaning you can immediately restore 75% of your action skill CD by popping through these 3 charges. This allows us to not have to worry about any action skill cooldown reduction in our trees while having next to no downtime.
AF1000
This is a great option if you want to have something more offensive in this slot. Getting one of these with some sort of damage buff like Hard Hitter means you can have that buff active for a very long time. If I feel like really tryharding for whatever reason, I'll swap between both these repkits during combat. AF1000 for while I'm in Arc Knives and swapping to the Triple Bypass when I need to get back into it.

Shields
There's two main options here, both felt about the same to me in practice. I recommend trying both to see which you like better.

Onion
This shield offers us a decent bit of defensive value, giving 2 seconds of immunity each time an armor segment breaks. it's not much, but it's more than enough to keep us alive through combat and let us tank some things we otherwise couldn't.
Timekeeper's New Shield
TKNS is similar to the Onion, though instead of immunity acts more like a general stat stick. It gives us flat health, health regen, and damage reduction. Again, lets us stay alive through combat.

No matter which you choose, a defensive option in this slot is ideal. We could get more damage through the Heavyweight, but damage doesn't matter if you just end up dead. And as of right now, it's very difficult to be in an enemy's face and not die either to them or to something exploding. We want to stay alive as much as possible because if we go down, so does Arc-Knives.

Ordnance
As mentioned in the class mod section, your Ordnance choice is going to have to change depending on if your Esgrimidor has points in Booming Business.

Slippy
This is the most ideal Ordnance. While you aren't going to be using it often, it's easily best in slot just because it's the one we're boosting the most.

Throwing Knife
If you do have points into Booming Business, then you want something that doesn't deal splash damage. For that, I tend to just use any Throwing Knife.

Weapons
Something corrosive, something incendiary, maybe something shock.
Ideally, a corrosive and incendiary Maliwan. This allows us to easily buff Collaborate Ignition against any health type.

To note here as well, blades currently seem to STILL be a scam. They'd recently been made to actually give a melee damage buff (previously they were pretty much cosmetic) but this DOES NOT apply to Arc Knives. Along with that, bladed weapons swing slower. So even for meleeing outside of Arc Knives, while they do buff your melee damage, it'll likely lower your DPS with the tradeoff of higher damage per hit. If you plan to only ever melee while in Arc Knives, there's no reason to specifically farm for a bladed weapon.
Currently it seems that only bladed Maliwans actually provide a melee damage buff at all.

3/3 Reel Big Fist
Additional raw melee damage along with some more AOE for mobbing. Arc-Knives are already somewhat AOE, but having even bigger area with even more damage can't hurt.

2/3 Action Fist
Again, just some more damage stats. Nothing too crazy, but its the most stats we can get for the two points. You could go for something more defensive like Baker or Risky Boots but they don't really feel necessary.

Groundbreaker
Just an absolutely cracked Specialization. If you remember it from BL3, it'll feel very familiar.
Can't stack off melee damage, but we get around this through bonus elements. Because Groundbreaker itself is melee and we have bonus elements applying on our melee hits, our bonus elements benefit from Groundbreaker's damage and then feed into the next hit. This lets us snowball our damage HARD to take out tougher bosses.

Bear Arms & I Am A Gun
As mentioned throughout this guide, these skills let us get some crazy value out of some interesting skills in our green tree such as Diamond Hands. It also means we can get some very minor value out of Enhancements.

Now With Caffeine
Unlike other cooldown reduction, Now With Caffeine instantly replenishes 25% of our cooldown on activation. This means with the Triple Bypass we can immediately get 75% of our action skill back and never have to worry about cooldown rate from elsewhere.