You are using Sorcerer in a WRONG way.
First of all, it's an offensive support class.
Secondly: unless you have a FBH Card, you won't be anywhere near to beat a fully geared RK.
You're also bad at Psychic Waving people. Ever heard of Crystallization + Ventus 2 Psychic Wave with Insignias?
And lastly, your stats and gears are so wrong, and you're wondering why you're getting OHKO'D. You're not using a shield neither a feather beret, what's wrong with you? May I ask you as well, where do you play?
I wouldn't be surprised if you didn't use Dispel before starting a battle with an RK.
And now for the suggestion part:
Stats:
1~25 STR just for carrying stuff and certain resistances.
15~40 AGI for the aftercast delay. You might also need an Awakening Potion.
110~120 VIT to have more than 30k HP. Seriously, 100 VIT? No wonder with 1 Hundred Spears.
105~115 INT for the damage; Psychic Wave's damage is heavily affected by INT, MATK increases its damage by a minimal amount.
115~120 DEX for the cast time; I'm actually wondering here if you use +20/+10 Foods and if you manage to reach instant cast (which, in any case, you probably can't because you're not running Ventus)
1 LUK; WHY THE f*** ARE YOU RUNNING LUK?
Now for the strategy if you really want to succesfully deal with RKs.
-Don't use Agni.
-Wear a goddamn shield. Valkyrie's Shield preferrably since you get that 20% Fire resistance. Thara Frog Card as well.
-Change your headgears: use demihuman reductions instead of MATK amplifiers. Feather Beret, Blush of Groom, Gentleman's Pipe.
-Learn to swap gears, if you think you got your enemy locked down, then you can change to Vellum Arc Wand, but for your main weapon, I suggest you use a Combat Knife with DEX or INT enchantments.
-Change your accessories, use a Smokie or Zerom card on Orleans Gloves, they are really helpful ever since pre-renewal.
HOW TO DEAL WITH PLAYERS IN PVP 101 AS A SORC
Fiberlock is the only thing I acknowledge from you, keep using that. But you gotta change your style. RKs probably main a Valkyria's Shield as well, so they also have a 20% Fire Resistance, which means a no-no for Agni Psy Wave.
Arullo and Vacuum Extreme are decent skills but they won't stop your enemy, try using Dispel against RKs at first sight, even though they won't do much for them, it'll surely remove basic buffs like Agi Increase, Blessing, Assumptio and what not.
If said RK is using Millennium Shield, you can Fiberlock + Cloud Kill them to get rid of their MS.
They can also use refresh, so they'll most likely use it after a succesfully casted Arullo. Try using Diamond Dust against them. They have a lot of VIT, but the skill itself has a 30% of Crystallization chance, plus 17% more for you being (I hope) 175/60, that means you have a 47% of Crystallizing that RK. Now if what I said is correct and they have lots of VIT, you might still have 25% or less, which is still high.
You might wonder WHY NO AGNI HURRR MUH FIRE PSYWAVE. The answer is simple: most people don't run Wind resistances, Valkyria Shield does not have a Wind reduction and Crystallization increases all incoming Wind Damage by 150%. Instead of running Agni, try running Level 2 Ventus to endow your Psychic Wave to wind. There's also this good bonus where you eliminate your fixed cast time (at least on sorcerer skills) when using her this way, also you get +5 ASPD.
The reason you need to lower your MATK and increase your resistances is because Sorcerer is the 3rd most tanky class in the game, just below RG and RK respectively. You can, with the right gears, survive an RK easy.
You can also use those delightful ground skills which SAGE JOB gave you, like Deluge, Wall of Fog, Whirlwind, etc. to stay in a defensive setup and avoid your enemy for a while. Please also use Safety Wall, best skill since 2002 just after Pneuma.
Try using Insignias, that's what they are made for.
Hope it helped.
