There is a saga to this one, which goes like this:
Once upon a time, the spike served at the railway, securing successfully the rail of course. And Spike was happy for decades, but the day came when the company changed the old wooden sleepers to new reinforced concrete ones. And suddenly our little hero found itself in a scrapyard, with thousands of his comrades, without a job and without a future, ripped from their pride. The horror of melting in, hung above their steel heads as the sword of Damocles. But then, unexpectedly luck shined upon his rusty face. His tiny metal heart filled with joy once again, when someone with a great amount of imagination picked him up from the muddy scrapyard floor. The gentleman undoubtedly had a holy vision of what this little spike and their brothers in arm could become, and praise be mighty Hephaestus, he delivered them to me.
Than he transformed in the divine, golden flames of my humble forge, never forgetting the past!
Hence, he was given a second life, becoming a knife
But this is only a legend, kids.