Strong Minded is a high-level talent within the Mental Fortitude tree. Its effect is pretty good - re-roll a failed test to resist psychic powers - something that any character could benefit from.

Bastion of Iron Will adds a bonus to resist psychic powers, based on the character's Psy Rating. Obviously, not every character is going to benefit from such a talent (ie. all non-psykers).

The problem is that to purchase Strong Minded, you first need to purchase Bastion of Iron Will. This essentially means non-psykers have to spend 600xp for a talent they can't even use.

I suggest swapping the positions of Strong Minded and Bastion of Iron Will on the talent tree, as well as swapping their prerequisites (Willpower 55 & 60). This would allow non-psykers to purchase Strong Minded entirely through talents that benefit them (Cold Hearted -> Nerves of Steel -> Iron Discipline -> Jaded -> Strong Minded).

I strongly believe Psykers should get their own Talent tree in addition to psychic powers. That way, no psyker-exclusive Talent would ever clog up any generally available tree.

Agreed - this should indeed be changed.

Not sure though if a simple exchange would do the job.

I also prefer giving psyker their own small tree and separate it from mental fortitude (give mental fortitude 1-2 replacements instead, e.g. Armour of Contempt).