Hopefully a cache of original work.
Given that Psi is known to be able to manipulate thought, emotion and memory, it is therefore theoretically possible for a Psi sleight to be used to warp and shape minds - in this post, we will be focusing on it being a potential vector for an Ex surgent strain.
Presuming this hypothetical sleight works similarly to other strains, it could function in a myriad of ways.
Maybe a team passes through a seemingly empty area, only theirs actualy a hidden nanoswarm or other Exsurgent probing their Egos so carefully that they never notice it. Maybe the Exsurgent plays with their unconcious thoughts, driving them to unwittingly further it's own goals. Maybe it warps them into sleepers, activated by a signal conceived by the Exsurgents alien logic - or flat our rewrites their Ego entirely. Or maybe the Exsurgent doesn't make use of such power and the team simply acts in the alien manner that usual Exsurgents do.
OVERT: Given that so far the Exsurgent virus ends it's eclipse phase before it can infect larger groups of people, it wouldn't be too presumptious to assume the pattern will hold. (Or, at least hopefully).
An overt use of this power, would be to capture or otherwise catch a morph with their pants down and then commit heavy assault through the sleight. No one might suspect anything, maybe the new Exsurgent quickly converts it's friends, maybe their friends notice the victim acting strangely. Or maybe all of the group is ambushed at once, they're all converted and they agonizingly set out to obey the virus.
Either way, something like this would mean the "unhackable" state of a biological brain would be rendered mute. No one would be safe from direct mind hacking.
Make sure you're wearing your tinfoil hats at all times my friend's.