[Neomi]

BG2 - TOB spoilers...
.
.
.
.
.
.
.
.
.
.
.
.
The ability to "Use Any Item" which is a thief HLA does not necessarily allow you to backstab with said item. Yes, it means that your thief can wield the Holy Avenger just the same as it allows you to read from scrolls or use wands. Yes, you can go invisible and whack someone from behind. But no, it does not apply the backstab multiplier to that attack, which kind of makes backstabbing pointless (other than to get a free attack on some unsuspecting sod).

The point SixOfSpades made is that the backstab multiplier will only be applied when a thief backstabs with a weapon normally useable by thieves. The Holy Avenger (which is coded to allow only paladins to use it), and all two-handed swords for that matter, can not be used normally by thieves, therefore the backstab multiplier is not used. The same thing is true for the Staff of the Magi (much to the chagrin of my F/M/T). Since it can only be used by a mage, it can not be used normally by thieves and thus does not permit the backstab multiplier to go into effect, even though other staves can be used for backstabbing...