Hemalurgy and Intent

So I'm on a whole cosmere reread number like 5 and It only just occurred to me, to make a hemalurgic spike it needs to be in the correct place in the body and it needs to be done with Intent to do so.

So how is it that the sword that happened to break in spooks chest by a random soldier turned into a hemalurgic spike? Either the sword itself had previously been given a hemalurgic charge or the soldier had to intentionally break it with Intent for it to become a spike, which doesn't appear to me to be what happened but I could be wrong

So basically, how did this work?