I found some setups with Arbiter. I think the ability to tack on a grenade after damage ender limits the desire to dig deeper into HKD setups, while Arbiter has a really strong meaty game. I’m sure variations of some of these have been done in combo videos already, but I felt like putting all of these up in a place where nobody will see them.
I’m pretty sure that for these setups, Arbiter is safe from the grenade regardless of opponent. Any grenade setup you find with Arbiter should be attempted from the P1 side, because the grenade’s hitbox is centered on where it sticks to the opponent, which is always on the left side.
Grenadeless safe jump
Fortunately, if you don’t tack on a grenade (which you don’t have to do every time), you get the same amount of knockdown advantage for forward/back throw, as well as his HKD ender. This particular timing can be tough to get.
Throw+Grenade safe jump
Unfortunately, if you tack on a grenade, the amount of knockdown changes slightly between throw and HKD ender. This safe jump is a lot easier to time than the grenadeless version, but you might end up limited in follow-ups if you don’t have overshield (so maybe don’t tack on a grenade every time). Empty jump throw and empty jump low (can be jabbed/thrown) xx special will both recapture.
Again, why should you always tack on a grenade when you have such strong meaties? This setup will get df+HK to hit on either the 5th or 6th active frame, potentially making it +17 on hit and +11 on block. Doing another df+HK will link on hit and frame trap on block.
This also works for his f+HK overhead. Conveniently, df+HK and f+HK have the same final active frame, which is frame 18.
This is more limited if you don’t have overshield, but works the same. In the gif I linked MP, but at +17 you should be able to link HP and either confirm with the sword target combo, or stop and keep your +4 advantage
Grenade CH recapture
One downside to using df+HK and Cl.MK is that one hits high and one hits low. Cr.LK hits right in the middle to beat low/high invulnerable wakeups, and is conveniently +12 on counter hit for whatever reason. This means it links into MK buttons. It also has a short recovery, so even on block you can sneak in a Cl.MK, even though it’s not a true frame trap. This is a weird combo that recaptures, and can be made safe by cancelling into overshield.
I can’t comment on the usefulness of these mixups, mostly because Ranked players can’t find it in their hearts to block the simpler setups, but they look pretty cool. The Cr.LP chains prevent backdashing and hit mid to beat high/low wakeups. Arbiter’s jabs are 0 on block and recover really quickly, which can let you get away with stuff. His chain jabs also aren’t block strings, meaning that an opponent trying to interrupt after the 2nd jab will get counter hit by the third, then mixed up with a safe low that the grenade will confirm. The jab x2 into light overhead is also safe and grenade confirmable. You can also insert a command grab in here, but you only get a soft knockdown and mediocre damage.
CH meaty combo
This is just a grenadeless counter hit combo that shows the absurdity of Arbiter’s manuals. His medium overhead easily leads to any manual.
This is a cool combo that does a lot of damage and includes a really tricky lockout bait. The front part of it is also pretty useful. The MK is early enough to counter hit wakeup throw tech/button, the M overhead will combo on hit and frame trap a button, the grenade acts as a safe confirm (safe for Arbiter on block), leading to any manual on hit. To perform the razzle dazzle portion of the combo will require overshield and cost you 2 grenades, 3 bullets, and a bar of meter.