(Because of Class bonus and already high Str output and extremely high raw Min-Max (which affects most of your dmg) you don't need to max brandish just to remind)
Incase you arent Master lvl yet and not having starter lvl50 cards then get Scratch Thief Card x 5 (Thats like 17Vit per card and +6to other stats per card). Those gives a nifty boost to hp.) You can find those cards from a mob called Scrath thief LOOTER (note that its called Looter and that monster drops that card only) in Road of Blessings (Map after sograt desert and is before the entry to morroc)
Once you got to Master lvls you can get
A) Upgraded versions of RoB cards aka Blue cards related to Fortress of sandarman. These cards wont drop in Sandarman tho (or just the normal 0,0001% chance to get it which is like once in a millenium).
But you can fuse these cards by fusing 5dif cards obtained in RoB and hope for the best.
OR
You can buy these cards from Auction House if you know how to make/you got a lil bit zeny (Theyb) arent expensive at all tho)
Or for the lolz
You have a chance to get these cards from Unidentified Card too (Meaning its an item which after opened will be a RANDOM card altho it wil not drop every cards). You can get those
1) Trade blood points from PvP events WoE and Coosseum and Jehoons training ground
2) Farm monsters in fallen fortress drop rate is low but nicely geared ppl can farm them in an hour if they want to and drop rates are favoring them.
Then theres the superduper expensive way
Basically getting a card set from Raid map Abaddon of Despair where raid bosses drops green cards (mobs too are needed for the full card set) and to fuse these green cards with extremely low chance to get that blue card whic vis reflected on the cards price making them extremely expensive so thats why you dun see ppl runing with them alot.
And then theres a cheaper way too...
Mobs in osiris tomb drops cards too which basically boosts 0-2 stats so price is cheap too they can give you what you need but cant give everything which makes them a tad useless to ppl with good card sets.
As a tank warrior tho your only interested in these stats pretty much
INT
AGI
VIT
So id say get scratch thief then evolve them to Osiris mob cards which boosts pretty much Int,Vit and after you dun like to grind/have free time you can get better cards which focuses on many stats. (Pretty much the more the merrier)
Stat allocation between INT <-> AGI <-> VIT (Vit isnt necessary cause already high defense and VIT from other sources like Gears + Cards + Titles + Hp from costumes + Runes everywhere)
STR Boosts overall damage yes. But the increase isnt that high and also the Hit given from it you dont have to worry (Your gears itself prettymuch gives you Hit enuff to almost never to miss altho you will always miss if you arent lucky
)