Todd Roybark
Hero
A different thematic feel doesn't have to mean different mechanics though.Bolded the ones relevant to me - the "sci-fi feeling" thing isn't exactly right, but a DIFFERENT feeling to D&D-style slot-magic is important.
An Echo Knight that is described as using Psionic Energy is straight out of Remote Viewing lore.
The mechanics are a means to advance play, not a way to shackle it.
Take a cleric, use the Spell Point option...swap out some spells. Replace Channel Divinity with Psionic Recovery, which is just like Arcane Recovery but for Psionics.
Allow Psionic Recovery to get multiple uses per Long Rest, like Channel Divinity.
Swap Divine Intervention for a Magical Secrets like ability.
I'd play that. Would you play that class? The engine works...the frame is solid.
In car terms Psionics is an appearance item, like a fender.
It is easy to modifier, and won't wreck the car.
Dont haphazardly start modifying an engine, though.
Let the designers use what we know works.
The U/A Psi Knight feels like a Psionic Warrior....not the weak caster that the Psychic Warrior was in 3e. It plays like a 5e Battlemind, especially with the Telekinetic feat.
I think you can achieve the feel of play you want with all the classes 5e has now,mic you are willing to modify and be open minded.
Of course, you might feel differently, and I would be interested to know, why if you do.