Bizarre timing this, having spent all day playing my first set of games with some of Thorin's Company in a mini tournament and including Oin (Southy I don't see any reason to tell the good people of the internet where I came in said tourney
).
Personally, I think the wording is pretty clear, "re-roll a single dice in a fight" it makes no mention of a duel, nor does it imply that it works in the same way as a banner. This is a unique special rule, not a model that counts as a banner, therefore I believe the rule can be used to either win the fight or wound.
However, assuming that is the case then you must also assume that you can use the rule to re-roll a Heroic Strike, a Piercing Strike, a Fate roll or indeed, any dice involved in a Fight.
That's certainly how I see it and how I will play it (assuming the opponent agrees beforehand) but of course it's just my opinion. Bear in mind that this isn't an automatic rule, it's a rule that can only be used once per turn and only 4 times per game (assuming Bombur/Gandalf etc. don't restore Oin's Will) which seems like a reasonable special rule.
Finally, despite all these possibilities, having used him in 3 games today, I never once wanted to use it to wound. As you only get so few chances per game, I found I wanted to save Oin's Will for those horrific turns where Thorin rolls 3 1s when he's trapped and needs a hand and not for the chance of doing an extra wound. Re-rolling a Heroic Strike however, could well be game changing...
Just my 2 cents
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Finished 2nd in the 2014 GBHL. My Wife's so proud
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