Ya know, if I actually had a backyard to do it in, I'd make Inquisitor-like spikes. Nice and full sized, with a nice impression of the metal's letter from the steel alphabet on it's head.
I'd sell them with a card telling people that, while Brandon Sanderson is an amazing writer, Hemalurgy doesn't actually work and you shouldn't use the spikes to hurt or kill people. Everyone would listen, right?