There's also a level of creativity that has to go into using Psychomancy. Using my robed psychomancer from before, he didn't immediately reveal himself to be a Psychomancer. He tried to pose as a Demonomancer first and summoned "Demons", which were suppose to distract you while his actual soldiers killed you all. Of course that didn't pan out after Ssarak made it clear the demons didn't exist, but even if he didn't someone may realize that they aren't what they seem if blows doesn't hit anything solid and even if they slashed at you, you wouldn't feel the hit. Personal effects like invisibility are more useful because then you aren't trying to trick anyone, just making sure they don't see you. And even then it's taxing to keep it up for long.