@rattobr
You basically have to pick your poison in C2 if you want to make a Cataphract. Going Peltasta gives a nice defensive active and the option to go 1h + Shield for extreme tank mode. Barb Cataphracts are really awkward, see the only Barb C1 skill you can use while mounted is Helm Chopper, but Helm Chopper is simply such an incredibly amazing skill (hits twice, has overheat) that it gives me doubts. And I personally hate buffs that arent up 100% of the time (Hello Lv5 Finestra).
All in all, that is a super weird build and I wouldnt suggest anyone going it at this stage.
@Mitsukai
Hello yourself!
Ok so if you want an Autoattacking build, go for Corsair. If you take the Barb/Doppel path, you’ll get much, much higher damage from skills. Also, Swordsman buffs do work on skills, but getting C3 is a bad idea unless you are hell bent on PvP. This is because getting higher ranks in Barb will make those skills deal extra damage. And Highlander’s Cartar Stroke is insanely, insanely good.
I would recommend the cookie cutter Swordsman > Highlander > Barb3 > Doppel. If you are more interested in an AA build, check out some of the Corsair builds.
@GingerSnaps
I would just follow this build as best you can from C3 onwards. (Ignore the Highlander part, pretend its C2 Swordsman XD)
@yami_shoumetsu
I know you didn’t directly ask for me for assistance, but I feel like I need to pipe up and say that isn’t a very optimal build, mostly because the damage you get from swordsman buffs is tiny compared to the massive damage from Barbarian skills. (That’s ok though, this is why there is a beta!) Like my good friend Mr. Snaps, I’ll go ahead and point you to this build which basically a better version of what you have: http://www.tosbase.com/tools/skill-simulator/build/sak3d3ekvi/
@psirukasu
Oh stop it you 
But the main reason Catas (Only DPS Catas, mind you) are tricky to build is C2. One one (average) Highlander skill is usable while mounted and the 2H Sword passive isnt useful. Peltasta is a great choice for Tanky Catas, but offers nothing for DPS. So you’re basically left with Swordsman C2 which is really bad unless you like PvP (somewhat ironically Cata’s are supposed to be pretty darn good in PvP, but even then C2 Peltasta is likely better in PvP)
Anyway if you want to do damage don’t invest in anything but DEX (Possibly some STR later on). I went ahead and made what I think is a much better build for a DPS Cata:
In the near future I am probably going to make a bit of a Cataphract guide or least PSA, since they have a lot of hidden strengths and weaknesses. For example, Earth wave seems to gain more hits as you level it up, meaning it’s actually a lot more powerful than the numbers would describe. The best Catas are probably tanky ones, Cata is a very, very, VERY good choice for tanks.