I think I might give a few pointers or at least we can engage in some brain storming.
I’m going Doppel C2 myself as well, I simply adore 2H swords and that’s my main reason. My build is going to be Pelt or High > Barb C3 > Doppel C2, OR it’s going to be yours.
So what I’m about to say is coming from input from others who run with your build as I have no deep experience with Highlander.
Sword 1:
I’d take 1 level in thrust. We have no pierce attacks at all, this helps versus some tanky monsters while leveling since bonus damage. It’s a second off of your Pain Barrier.
Pelt 1:
Umbo Blow is great, Swash obvious and Guardian too, just to help you level early. U probably will only use this while leveling, not important.
High 3:
Cartar, only get level 3. Don’t need more. This ability was nerfed from it’s OP state. 3 is enough.
Crown, at least 1 level. Shock apparently works wonders vs casting monsters, acting as a silence. It also works with your later doppel levels.
Cross Guard, its literally for convenience. Unlike normal shield guarding, cross guard gives bonus defence so it works with doppels deeds later on since deeds reduces defence from ur stats, not buffs.
Now the important stuff.
Crosscut, use this with Skyliner obviously. Bleed scales with STR but not that well.
Skyliner. It might get a cooldown in the future but I heard it will have 3 Overcharges.
Skullswing, apparently reduces a massive amount of defense from monsters. Get it. The base damage seems low, and if you pick it just for the effect for 1 point.
Moulinet, fancy and sexy looking ability. Multiple hits so it scales quite well.
Vertical slash, just another hit to the arsenal.
Honestly though I have no real experience of High 3 since I went Barb 3 in iCBT but their skills all seem solid.
Doppel 2:
Cyclone at 10, no brainer.
Zornhau scales well with levels, no harm at maxing it. Low ish cooldown, applies shock. It’s good.
Zucken, ok this skill is weird. The level one is 8 SP cost and level 5 is 180. This is not a bug. I would leave this at 1 because the flat damage increase is just 100 per skill level and not worth it at 5 since 180 SP for a Sword is too expensive.
Redel, another lovely hitter.
Deeds, personally I’d go as high as 9. This way it would be on at all times (buff duration longer than cooldown) but 90% speed and only having 10% of your defense seems like a death wish. Honestly though if this skill didn’t require GETTING HIT everyone would max it.
Double pay, it’s fun. Get it man. Apparently hilariously bugged where if you activate and your party kills a boss everyone gets 2x exp even if you don’t do the final hit.
Punish, this is a nice extra hit to do if you down something. It flashes on the screen when you walk near someone who is knocked down too. Not needed, but another nice skill.
Mordschlag, ok I would only go 1 point. This skill is a guaranteed critical hit on CLOTH type monsters and you as 2H gain bonus vs cloth. It kicks mobs way back so use it as a finisher. Worth the 1 point since going all the way to 10 just gives more flat damage. OVERCHARGES too.