this is my feeling too. on the animal isle (forgot the name, it is in the north and there is one guy that searches for a treasure) I forgot to save at all, and in one of the last battles the remaining archers commited suicide going on a trap and I didnt have the chance to resurrect all killed units. This way I lost +3 might runes, over 7 crystals and one wander scroll, replaying battles gave me only gold, so I remember that moment very well
I checked the file where the probabilities of item/rune/crystal/money are, but they look ok, random number between 1-100, first probability of an item (looked something like that k=Game.random(1,100)
k=k-3
if k<0 than ... gives item (from a list, if the list is empty than money), the list is full of lvl 1 -3 items, the best item I got from the battlefield is the sword of equlibrium on shettera or ogre club (finishing the whole set that way) on elon
elseif
k=k-5
if k<0 than ... gives runes (1 to 3)
elseif
k=k-3
if k<0 than ... gives crystals
elseif
k=k-5
if k<0 than ... gives scrolls (1 to 3)
elseif than ... gives money
it seems that the chance for an item is 3%, for runes 8%, for crystals 11% and for scrolls 16% (I hope I remember correctly the numbers
)