Although having a brief rulebook may be less intimidating, I do feel that The Hobbit's is just a wee bit too shallow.
You roll up five dice for every combat. One of final (level 4) event cards allows you to re-roll five dice. Almost any player by that stage will have increased their cunning score and will have re-rolls available to them. To me, this is a good indicator that you can re-reroll the same die should you not get what you require. That's as much as ten re-rolls if you have a full cunning track! I assume you just can't re-roll any die you wish to keep.
I suspect not quite right. The cunning allows ONE single re-roll of up to five dice. The ability card that grants re-rolls would be the same thing. So possibly TWO re-rolls of up to five dice, not TEN re-rolls of single dice.