This is my vote for Omen’s worst matchup in Season 3. Here are some tips i have found.
—Stay on him the whole game.
-You do not get to throw any fireballs, or use Shadow moves, or slide if Arbiter has any resources.
-You need to jump and airdash as much as possible to get close. You can air dash OVER most grenades and carbine shots. And if you expect that they are beginning to get used to this, you can throw out a medium or heavy slide as a MOBILITY tool. You will probably only get away with it once, but it can give you good space.
-Forward dash as much as possible. After every throw, after every Knock down, and When you KNOW they are going to try to block.
—When you are far away:
-Threaten to move forward, and make them waste as much resources as possible. They KNOW that grenades are super good against Omens fireballs, so wait for the grenade, jump so they hit the ground, and then either: 1) If Arbiter stays full screen, just block the explosions. 2) If Arbiter tries to move forward too confidently, You can try a surprise jump attack.
—When you are in mid-to-close range,
-After every move forward, they may throw out a panic move. Arbiter has OK walk speed, and players will try to use one of his slashes as a mobility tool to get in close and punish your forward movement. To counter this, you should usually cancel every airdash, forward dash, and mobility slide into a block, and look to see if they panic.
-If they Stay back and wait for your offence, then you may start throwing projectiles to build corner pressure.
—When you are close range
–Perform Omens typical block-string. (Heavy Command move into fireballs) Against many opponents, it can be hard to guarantee that this will hit, but NOT for Arbiter. Arbiter is big, and has no fast moves, so he has very few options to get out of this. You can repeat the loop over and over again (something that is hard to do on most characters), go for overheads after, back dash after, or sneak in a forward dash throw.
#Do NOT Use any ender except the Orda Shield Ender! (out of the corner)
Arbiter has a TON of tools to keep you away and get some resources back, so if you ever get an opening near the middle of the screen, use the Orda Shield ender to get some VERY good close range set ups.
You can follow the ender up with any button, and cancel that button into Rashakukens, which will put you at a GREAT close range advantage once they stand up. That is the one i use.
Usually an Omen Player’s instincts are to use the other enders to push your opponent into the corner, but against Arbiter, you only give him more resources, and put him at a perfect range to use his carbine to lock you down.
—Offensive Summary:
Arbiter’s zoning counters Omens in almost EVERY way.
The only advantage omen has is that Arbiter’s resources are limited. You need to make them waste resources.
Once you are in, Arbiter is very similar to Aganos. You can keep him from moving, use ALL of your tools once again, and make his grenades damage himself if you are very good with the timing.
—Defensive Summary:
Unfortunately, Because you ALWAYS want to get close to Arbiter, The only way to have a defense is to make HARD reads on your opponent. Arbiter is similar to thunder at close range offense. Almost every thing Arbiter does can be punished with a full combo, but you HAVE to know what your opponent wants to do. Keep a cool head, watch for punishable slashes, get a PERFECTLY timed crouching LP punish, and then slide under him to put him in the corner.
If you face a VERY offensive Arbiter, the match will be a blood bath. What i mean is:
Omen’s best options against arbiter are extreme offenses.
Arbiters best options against an offensive Omen is ALSO extreme offense.
The only way you can get a FAIR and MANAGEABLE game against Arbiter is to force him to fight close range in the corner. So if you follow this guide, and get the Arbiter to play you at YOUR favorable spacing, then who WINS will be determined by who is in the corner longer. If you MAKE SURE its YOU doing the offense, you will find that fighting the Arbiter becomes much more possible.
#The Fight is extremely hard, and will NEVER be easy,
But hopefully this advice will help you make a 10-0 matchup turn into a nice 5-5.
Fighting Arbiter is a TOTALLY new fight for Omen. I hope this stuff help you guys! <3
(And by “Guys”, i mean: The 2 other people who play Omen besides me 
)
@FallofSeraphs76 @DulXboxOne
(Will add more advice if anyone finds it.)