Tachi also offer a good build with eva type, so we can "swoosh-swoosh" our katana without being hit.
Sorc as ur sub?
We are gonna max our eva so with Grimoire that have a eva stats on it, Eva build would be easier :3
Besides, we got sleep totem that helps us a lot.
Pro and Con Being Tachi/Sorc
Pros :
Maxing eva is easy with this build
You can be a range dps if needed
Sleep totem for crowd control
Cons :
No ultimate skill
Not a good dps if compared to Tachi/Wizard
Squishy if got hit
Status Build
Damage : Put all of my points here to make your dps as high as possible
Crit : Put your points here if u want to critical hit a lot, but you'll also a good crit damage too.
Speed : Put your points here if u want a faster cooldown and faster casting Iaido
HP : Put your points here if u think you are too squishy and need a higher HP Pool
Def : Put all of more points here, so even we got hit, we still "tanky" enough
Eva : Put your points here if u can't cap ur eva yet. But remember, your class buff is add crit and eva. You can always cap eva with buff class and buff food if you need it though.
Envoy Path
Here is the current envoy path at lvl 65
First envoy node that you should get is the "Blades Technique : Tide"
This envoy node will gives you a bunch of crit IF your hit is not crit but the buff will be gone if ur hit crit already. So this is why its not recommended to put any points on crit.
Second envoy node is "Charged Jump"
This envoy gives you Eva Rate 6% and Move Speed 8%
Third envoy node is "Blades Technique : Sacr... *can't see the complete name D:*"
This envoy makes Tachi able to stun from range!
Fourth envoy node is "Blades Technique : Soul"
This envoy makes Tachi a slayer, when opponent's HP 40% or below, they will get debuff Move Speed Reduce by 40% and Def reduce by 20%
Last envoy node is "Infinity"
This envoy boosts Eva Tachi very well, every times we evade an attacks, there is a 40% chance to deal damage to nearby enemies
Eidolon
Kotonoha is your best choices. Why? Because she gives a nice buffs at 3 stars. And also, she gives us buff for absorb HP~
Uzuriel and or Bel Chan is nice if u want a little critical boost
Skills Rotation
So basically there is no perfect rotation. This is just the suggested skill rotation for this build.
Note : While facing boss, make sure your Tachi bar is always full so we can use "Blade of Souls Skill" then "Swoosh-Swoosh Katana a.k.a. Original : Katana Flurry"
BOSS rotation skill : Full Cast Iaido -> Blade of Souls -> Bright Dragon Flash [Jump and Stun enemies] -> Swoosh-Swoosh Katana
Lure rotation skill : Just run till u gather enough mobs, then cast Sorc's Nightmare Totem then u can do the BOSS rotation skill
Absorbing HP skill : Luckily you got two skills, so use Sudden Thousand Slash and Sorc's Soul Draining Spell in the middle of your rotation. You also have Rejuvenation Mantra for a little help on healing
Skill Masteries
Soaring Flash Dance : Reducing Target Def for a better damage output.
Callousness : Adding some Crit and Crit Damage is always nice.
Multiple Iaido : Increasing Iaido's Damage
Extreme Speed : Adding Eva and Move Speed!
Break Defense : Another reducing Target Def
Sinewy Body : Convert ur Damage into Defend (in % depends on the color of the mastery)
Gears
Armor Equipment :
For lvl 1 - 49 : You can use anything you want, yeah, anything.
For lvl 50 - 60 : Use full requiem set for more Eva and Murfeo, Malodnak and Talamund Accessory at lvl 55 for 3% Eva and 8% Crit Damage Each Acc~ and for trophy u can use Argus (Green, Yellow, or Orange are good) and Gekasso's Trophy
For lvl 60 : Change full requiem set into full devourer set
Weapon Equipment :
For lvl 1 - 59 : Use green ones, any weapon that boost EVA 5%~
For lvl 60+ : Use crafted ones.. Katana's ST Weapon and Sorc's Analisa Weapon.. Why? Because it gives us EVA Boost 
Core Choices for Armor and Weapon :
Armor : Use Shadow Core (add 1% DMG and 1% EVA), but you can also get Martial (add 1% crit and 1% EVA) or Imperial for 3% Move Speed
Weapon : Nocturnal (Absorb HP) and Deadly (for 15% crit damage) is the best core but also the expensive core XD. For the cheap core choices you can pick Ghost for additional 2% EVA
Costumes Option and Card :
Headgear : EVA 1% with Enchantment Card Iaido Mastered
Face : DMG 2% with Enchantment Card Blade of Soul
Body : DMG 2% with Enchantment Card Bright Dragon Flash
Back : EVA 1% with Enchantment Card Sudden Thousand Flash
Weapon : CDMG 5% with Enchantment Card Dark Tusk Raid
Don't know how to get the card? Try to look at your Dragon Coin Encyclopedia, its only 3k DC.