As a Possessor in 1.5.1, I noticed that my physical power is sometimes (very rarely, I only noticed two cases so far) *very* much lower than it should be.
Possessor with (scaled) physical power of 81 assumes the form of Slasul with (scaled) physical power 88. In Possessed form, I should have physical power well above 100, but I only have 41 . Physical power is the only stat where I've noticed this - it also happened when I assumed the form of Aluin the Fallen where I got physical power 37 although it should have been ~90.
What I also noticed is that passive talents are apparently taken over indiscriminately from monsters, my antimagic Possessor cannot use active talents that are categorized as spells, as it should be, but he can use passive spell talents like incinerating blows just fine in monster form.
This might also be part of the problem for why my physical power is miscalculated when I assume the form of Slasul or similar monsters, because it seems as if Slasul's Exotic Weapons Mastery overrides my normal Weapon Mastery skill (in Slasul form, there is only one "Weapon Mastery" entry that shows up in my character sheet, and since it is at talent level 12 - I guess it's Slasul's Exotic Weapon Mastery), but it can't be the only reason because based on my strength value alone in Slasul form (Strength=241), my physical power should already be higher than 41...