If this is actually a reproducible bug I may take a crack at fixing it. The issue is that most obvious implementations of it require placing scripts on every NPC, which is a HUGE pain since the GECK doesn't bother to implement any handy programmer tricks like inheritance that are applied a pure object-oriented sense. (or in english, there isn't just one "master" NPC I can edit to ensure every NPC checks for unfair stat bonuses).
It'd be great if you could take a look at the bug, Yukichigai.
It's certainly easy enough to reproduce, as all FO3 and FNV companions are afflicted by it. Simply equip them with any stat enhancing gear and compare their values before and after a few inventory accesses.
Oddly enough, their stats don't max out at 10, but keep increasing, at least according to the console. For example, in my last playthrough, Cass' PE was 11 before I had the opportunity to exchange her headgear for a stat neutral version.
My most vivid experience with this bug was when I clad Clover in Reilly's Ranger Battle Armor (Small Guns +10, AP+5, LK+1) as well as a bandana (PE+1). After a few trades her stats were insanely high, many of them in their teens (i.e. PE was around 16, IIRC).
Long story short, Clover eventually became so powerful that she easily dropped the Jury Street Super Mutant Behemoth with a standard Chinese Assault Rifle.
NB, I doubt it's really necessary to rescript every NPC in the game; fixing FNVs standard 6 humanoid companions would already be an impressive gameplay improvement most players would be grateful for.