Rework Valkyrie skills, cause she keeps switching to succession on each move of her. Can't seem to keep her in her Awakening. Very weird class, also having a hard time grinding with her. She just can't seem to kill enemies. 

Played with 90% of the rooster, never had such hard time with any other classes, this is the first. 

If you are having issues with her swapping to mainhand skills on some keybinds, you can check out the Valkyrie discord. The people there will be able to tell you which skills to lock to prevent your swap to mainhand. That way, grinding will be easier for you, and perhaps they might also tell you some good combos for grinding.

yeah as Minarya said it's not an issue that requires a Valkyrie rework, it's an issue that requires you to practice the class some more and perhaps check out the discord or ask some experienced Valk players which skills you may want to avoid or lock. Valkyrie does switch back and forth a bit, but mostly stays in awakening just fine during combos and personally I've never had the issue you're describing, definitely not to that extent.

If you mean movement wise with the Shield Chase in pre-awakening just make sure to slam spacebar to flow into Promptness awakening skill as this is basically a super core swap that works after almost every ability to get you back to awakening. Just make sure not to end your pre-awakening movement with Righteous Charge (pre awakening W+F) because that doesn't allow you to use Promptness out of it, save at least 1 Shield Chase to use after Righteous Charge and like I already said, slam spacebar to use Promptness and you're back in awakening.
Valk is a class where you need to very conciously use her movement because you can't really just spam it unless going forwards holding Shift+W in awakening, but this is very stamina draining.
Examples to help you get started: Awakening dash forward stays awakening, but after 1 awakening dash Backwards she swaps to pre-awakeing Shield Chase movement. Her awakening also has no dash sideways, only front to back. So if you do any dashes sideways that will also be pre-awakening Shield Chase movement. And as I said above, Spacebar after Shield Chase to use the Awakening ability "Promptness" and you're swapped right back to the Lancia.

I think you're just overlooking the biggest key on your keyboard, which coincidentally has an extremely useful and often used skill for Valkyrie awakening kit bound to it that makes her kit flow. I can't really give many proper in-depth tips or combos as I don't main the class at all, but these basics should already resolve a lot of the frustration and difficulty it sounds like you're experiencing.

TL;DR: Spacebar, Spacebar, Spacebar! Just not after Righteous Charge (pre-awakening W+F)

Valkyrie has to be the one of the most difficult classes to figure out and handle.  I use Succession, and in order to get a good mob killing rotation going, you have to figure out the perfect pattern of her skills in order to be effective.  Very specific ones have to be used in a very specific order.  I main as Musa, who has maybe three skills in his rotation.  Valk has 6-7.  I wouldn't mind if she was easier to use.  Succ Warrior sure is.