I didnt have the opportunity to play the Closed Beta so i guess that ill have to ask for you guys.
Is it a good class?
I mean, i know and i already saw some gameplay on open maps for grind leveling up.
But i would like to know if he is any good to battle field bosses or dungeon bosses.
I dont want to pick a class where i wouldn’t be able to find a party to this things.
And i guess that i was going to build
Swordman - Peltasta C3 - Squire C2
It is a good class for Tanking/Supporting Party.
You will be the so-called “Legendary Angry Wall of Meat” of the party.
Though in the early game, no one really needs a wall of meat to level so you need to play hard or find a good wiz to party. Though after you reach the chapel, you may start to shine! 
And yes, that build is Good.
This is my future build for my Squire. I have the option too to remove 5points from Butterfly and put it to max my Swash Buckling. But Butterfly can add to the dps of the party though if you really want to build pure tank, put it on Swash Buckling.