My take will be a Tank that will focus on Counterattacks.  Its weapon will be Katanas (and it's relic will be Masamune). Swordsmaster will be the base class and  Samurai will be the Job. It is based on STR.
The Counters will be  buffs that trigger upon taking a specific attack (Think a specialized  version of Perfect Dodge) and most of the skills will be based on the  naming conventions of the Swordmasters skills from BD (being based on  parts of figures of speech, with most of the corresponding buffed named  after the missing part of the figure [Except The Road Less Traveled  which is an except from a Robert Frost poem and Ummovable Object which  will have the same name in status form and with the other half of that  phrase being another skill]). All counters have a 25 second cooldown unless otherwise stated
Class Skills
- 1: Spirit Slash: 100 potency basic attack
- 2:  Nothing Ventured: CD that gives a status: "Nothing Gained". 20 second  buff that halves damage from a physical attack and hits the one who used  the attack with a 50 potency attack
- 4: Natural Law: 120 potency attack that can be proced by Spirit Slash, at which point the potency becomes 150
- 6:  Before Swine: CD that gives a status: "Pearls". 20 second buff that  haves Magic damage and hits the caster for 80 potency.
- 8: Purge of Honor: not a buff CD, just the usual 200 potency only available when mob HP is at a certain threshold skill.
- 10:  Sword's Code: 180 potency that can be proced by Spirit Slash, in which  case the Potency is 240 and you get a DoT on the target
- 12:  Early Bird: attack that adds a DoT to the mob, called "Gets the Worm"
- 15: Cornered Rat  (quest): CD that grants a status: "Bites the Cat". 20 second buff that  triggers when a teammate is attached while they're under 30% HP, halving  the damage to them and directing it back to the aggressor at 80  potency
- 18: Know Thyself: unlike the rest, this is just a buff skill that increases the potency of Counter skills
- 22:  Squeaky Wheel: Grants a debuff to the mobs: "Grease". Debuff increase vulnerability to magic and also adds Slow
- 26:  Abyss: CD that grants a status: "Gazes Also". 20 second buff that  triggers upon your next attack and stuns the enemy
- 30: Timber (quest): CD that grants a  status: "Make a Sound". 20 second buff that triggers upon your next attack and silences the enemy
- 34: Honor and Glory: 200 potency attack  that can be proced by Natural Law in which case the Potency is 250 and  it has a 20% chance of proccing counters.
- 38: Haste Makes Waste: AoE attack that has a potency of 60, adding heavy to  affected mobs and increasing their skill speed (for triggering counters)
- 42:  It Takes One: CD that grants a status: "To Know One". 20 second buff  that triggers upping taking a deadly hit (and under 30% HP), nulling the  attack and directing it towards the opponent for 6x the potency. Has  the 2nd longest cooldown period of 5 minuets
- 46: Free Lunch: A CD that is akin to Goad and Apocatastasis; you cannot use  it on your self but on your teammates. The effect being a buff that  makes spells cost no MP for 5-10 seconds
- 50: The Road Less  Traveled: CD that grants the party a status: "All the Difference". 30  second buff that triggers upon taking powerful move, it reduces the HP  of those hit by it to 1, but makes them immune to all damage for 2  seconds. Has a cooldown period of 10 minuets, the longest cooldown of  the class
Job abilities:
- 30: Multitask: A CD that  grants a 25% chance to follow up a skill from an autoattack or a  counter. (Meaning that while the buff is up any skill can proc Purge of  Honor, Natural Law, Sword's Code and Honor and Glory, each with their  whole effects)
- 35: On The Wall: CD that grants a status to  anyone in the party (including the caster): "Mirror Mirror". 20 second  buff that triggers upon taking damage from their own spell (as with  Before Swine or Reflect) allowing them to redirect the spell back to its  original target at half potency.
- 40: Unmovable Object: Stance skill. Counters gain more enmity and you get 20% HP based on the damage counters do.
- 45: Bushido: an attack skill that can only be procced by a counter. It has 250 potency.
- 50:  Unstoppable Force: Skill that removes all defensive Buffs, Unmovable  Object and active counters to boost the party's Determination by 50%. Must be procced by using 5 successful counters.
The  traits will consist of enhance STRs, increased duration for counters  and free lunch and a chance to proc a random counter whenever one is  triggered, as well increased emity on counters