Is there any case law that supports the argument that a hockey stick fell into the face of another player's eye injury?

The short answer is No. Having found that what happened was unintentional, the question that remains is whether it was negligent. Both parties cited a number of cases including Agar v. Canning (1965) 54 WWR 302. I quote a passage from that decision: What this all boils down to is an assessment of the standard of care expected of (the defendant) is these circumstances. Looking at the nature of the league in which the parties were participating, it is reasonable to assume the players accepted the consequences of an unintentional injury arising from a body check, or being struck with a puck. Occasionally a stick might fly up into the face of another player while the two were facing each other. These were the assumed risks. But it is a question of degree as to how much inadvertence in the use of a hockey stick amounts to negligence.