Nice words, but it is a rock. Functionality is not a valid test. Forensically? IOW your first sentence is "worthless"(don't take it personally, this is a discussion of hypothesis testing).
Your next statement does have the "look and feel" of a test. But what is the proper shape and size? I contend that what you mean is "Does it look like an arrowhead?" Okay, it does. So the next part of your test asks "does it exhibit the same kind of tool marks and patterns that the known arrowhead does?" Tool marks? It is a rock. Evidently the rock has chips removed by other rocks(or something else hard), since neither arrowhead, the hypothesized arrowhead nor the example arrowhead, display any toolmarks. Patterns, well yeah, they look alike, not exactly but alike. They each have a point. So I guess my hypothesis has passed the test. Has it?
That's a stupid statement. If it's supposed to be an arrowhead, and it's design is incompatible with fulfilling that function, then where is the "intelligence" of the design?