We know that Wolverine's claws are unbreakable and he can cut through any material using them. And Mystique can copy anyone one power completely, in fact in Days of Future Past, her capability is used to develop Sentinels.
In X-Men (first movie), there is a sequence where Mystique turns into Wolverine and tries to kill Cyclops. The original Wolverine intervenes and there is a fight sequence between both Wolverines. In the same sequence, when their claws strike, Mystique's (in form of Wolverine) claws broke into two parts. Why was Mystique not able to copy Wolverine's claws properly or does Wolverine somehow know some week point of his claws?