Thats weird and maybe some (good!) bug (?)
as you correctly observed it should only work in aspect of support
as for your build, i do dont recommend any build except support for endgame psi - you can even play it in a viable way for PVE
suppressionbuild seems fun at first but for PVE it is annoying due to low damage and bosses ignoring controleffects and in PVP people also ignore your CC (martrys skill & class skill) frist and then hit you 1 or 2 times and you die
i played psi as main for many years until i recently changed to paladin now and gave every possible way of playing a chance, ultimately making a full suppression build where i put all my statpoints nto health to become more tanky and got all the cc skills and so on, the result was like dying from 2 hits i lasted 4 times
so for now support seems the only viable way, sorry