From: Elementary 1.19
Event: A man, feeling as though threatened, wields an Xacto knife against his would-be assailants.
Reference: This is admittedly a stretch, but bear with me here:
In “Silver Blaze,” John Straker’s body is found with a peculiar knife stained with blood. It’s not a pocketknife or anything that would fold up in a pocket, but a “very delicate blade, meant for very delicate work.” It’s what Watson calls a “cataract knife” with a long handle and a small triangular blade. The investigators think it odd that Straker may have used it to defend himself, but he had kept it on his bedside table for awhile. Apparently it was the closest weapon to hand. Or was it?
I mean, is it too long a stretch? I don’t think so–I think the Elementary writers are savvy enough Sherlockians to have done this on purpose.