Following Okuza's statement I took a few minutes to look at previous FF jobs and the end result is:
Magic Knight
Job abilities -
lvl 5 Fuse - Allows the user to perform a random elemental spell when
(1 min timer) using a weapon skill to damage enemy.
lvl 15 M. Blast - Allows the next spell to hit the target with double
(5 min timer) the damage if used with Weapon Skill.
lvl 40 Double Cast - Instantly Casts the next spell twice without any delay
(10 min timer) or interruption.
lvl 60 Heavy Blow - Allows the user to Fuse an Elemental Spell with a
(10 min timer) Weapon Skill and deal double the damage.
Job traits
lvl 1 Mystic - Decreases Spell Interruption Rate.
lvl 10 W. Master - Allows the Magic Knight to attack faster with single
handed weapons.
lvl 30 Mystic II - Decreases Spell Interruption Rate.
lvl 50 W. Master II - Allows the Magic Knight to attack faster with single
handed weapons.
lvl 60. Split Attacks - Allows the damge of a Fused to attack to deal the
same amount of damage regardless of an enemy
monsters resistance. (Ill explain this more)
lvl 65. W. Master III - blah blah blah same as 1 and II.
lvl 70 Mystic III - I don't need to explain this.
Weapons - Sword B-, Axe B-, Dagger B
Spells (youll get a kick outta this)
1 - Torment (Increases Defense and has a chance of Petrifying Mob)
5 - Osmose (Drains a mobs mp to add to his own)
9 - Sypher (Steal a mobs Defense and adds it to your own)
10 - Fire, Water, and Aero
14 - Fear (Like Paralyze but stronger)
18 - Aura (Phalanx Pretty much)
All other spells are following this order. +4 lvls is a Tier II of normal spell from 1 - 18. Example. lvl 22 is Break II because its 4 lvls away from Aura. At lvl 20 The Magic Knight would learn Blizzard, and Thunder. At lvl 30 Fire II etc. lvl 40 Blizzard II etc. Magic Knight does not learn Tier III of normal Elemental Black Magic. Magic Knights Magic would be classified as Green Magic.
Strengths - Can wear Heavy Armor. Have lots of HP. Seriously becomes a Good Tank at higher lvls. Magic and Pysical attacking type of Knight. At lvl 60 split attack works if say you use Fire II and Split Blade with the fuse ability on a water type mob? Well instead of the entire attack being useless the mob would take the full dmg from the weapon skill. Vice versa, if the mob is weak to fire but not to physical dmg, it would still take the full fire dmg. Can wear Heavy Armor.
Weaknesses - LOW mp. I mean a Elvaan RDM with no mp gear at lvl 75 low.
Magic SUCKS if not used with the Fuse command. (They only have Tier III magic). Weak against Magic Attacks.
Well what do ya think? The Theme subjob for this would be MKT/BLM to increase the DMG of the MKT. MKT would be a good sub for PLD. I could also see BLM's using MKT as a sub job.