Average smamerage...
1)I am NOT a math nerd but I am fairly intelligent and despite the fact that math nerds tell us that statistics are wondrously accurate overall I have an inherent distrust of them. Yes the game does rely on a huge amount of math but whats impossible to "average" with the math is the way any given battle is actually played out. Specifically who targets who and how long it takes to kill them. As I understand the game engine if a player has 2 attacks per round and he kills an enemy in 1 hit he LOSES any remaining attacks and his next attack starts a new sequence (excep in the case of 3/2 attacks where it finishes the sequence started by the first attack.) Now its possible that if you are running scripts and the character automatically targets the next enemy this may not be so but without scripts many characters will just stand there when they have finished killing thier target until you redirect them or they are attacked.
In any event the playing out of these individual battles are in fact impossible to predict accurately IMO with the use of averages just becuase of the sheer number of variables involved.
As to my statement about having one superb archer and one mediocre one vs two excellent ones I fail to see why you keep referring to Imoen as "awful". She has higher than average dex and with good equipment can be a top archer in her class- just because she is not a warrior with warrior THAC0 does not make her "awful" she is about as good as a thief can be without the bracers and considerably better with them. If you insist on ranking archers strictly by their THAC0 and ignore their class (meaning only a warrior class can be "excellent" in your mind) then fine I will restate the obvious.
Why have one super archer and one "awful" one when you can have one excellent and one "decent" one.
In the end tho my real argument for giving the bracers to Imoen is not really about Imoen at all. I simply do not feel that Kivan needs them. I DON'T believe that in real game action his having those bracers makes a noteable difference in the number of enemies he takes out or the time he takes to do so. Perhaps he will use a few less attacks to do so and save a handful of arrows but I have played with him not using them and have experienced no problems what so ever he is still extremely effective and thus I have decided that giving them to him is a waste while giving them to a more mediocre archer can be a more noteable improvement in THEIR perfomance. In fact I think if you look at your numbers closely you will indeed find that adding the bracers effects to a character with mediocre THAC0 compared to adding the same effects to an excellent THAC0 the mediocre THAC0 gets a bigger "relative" boost...doesn't it???.