You're at the point where just being an inquisitor or party member is overpowered. It's not really knight enchanter specifically. Look at a tempest spamming flask of fire + 1000 cuts and then say KE is overpowered.
I haven't seen that combo yet. Are you talking over powered just in terms of pure damage or can a rogue with that combo be as unstoppable as the KE as well? In terms of damage, the KE is not the most impressive. My Rift Mage did more DPS by far.
What makes the KE overpowered is that it is invincible. A KE gains barrier very time he does damage to an enemy with anything - spirit blade, basic attack, spell, grenade, whatever. The spirit blade hits everything in a very wide, nearly 360 arc. Enemies behind me have taken damage from it, and barrier regenerates for every hit. The spirit blade upgrade allows it to deflect projectiles back to their source, so I don't have to worry about enemy archers. I kill them with their own arrows without even trying while beating on melee enemies in close range. As stated before, the spirit blade also does massive damage to Guard, so even enemies that should be tougher than usual are not.
It does take mana to use spirit blade, but with Combat Clarity you gain a bonus 50% mana regen for each nearby enemy so you never run out and always have enough to use the blade. With Veiled Riposte, enemies take damage every time they hit me while barrier is up, which is literally ALWAYS. Fade cloak grants invulnerability for two seconds, but that's not its true power. With Decloak, I also detonate when it wears off if I'm standing close enough to an enemy. The detonation does spirit damage in a small AOE and knocks enemies down.
My KE doesn't need any party members or potions. So far, nothing in the game has been able to kill me or even do any real damage to me. All I have to do is cast Barrier, then hold down my Spirit Blade button and watch everything die. No strategy or skill required, no focus required, just cast one spell then hold down a button until everything's dead. Whenever its available, I'll stop swinging my spirit blade just long enough to use Fade Cloak for a little extra dps burst.