Thanks to both of you. I never found the rule explaining that weapons were not used when defending. I mean, of course you cannot "use" it to add special effects such as more dice/results...
Then i remembered another thing: I read somewhere (on BGG i guess) that during a range attack, the defender could deal damage to the attacker on his defense roll if he also have a ranged weapon.
If this rule is true (we took the decision to use this one) the two rules cannot works together: You are "using" a weapon on defense on the second situation.
Does this second rule exists?
the rule you might be referring to is when an attacker attacks with a ranged weapon while being on the same tile as the defender. when the attacker loses the roll, the defender damages the attacker because they are on the same tile.