Paul is a blacksmith. He legally acquires high carbon railroad spikes from a railroad supply company. HE forges them to make blades, but they are also very popular in witchcraft as warding and protection charms, also in travel magick. Cheaper railroad spikes are NOT high carbon, but the ones Paul gets ARE and are stamped with HC on the top.
Sacred to Mars, iron is a symbol of mans will and desire to create, travel, build and destroy.
Railroad spikes also represent travel and hopes and dreams as before cars the railroads carried pioneers and those seeking new life and adventures across continents.
Many use them to pound into the ground around their houses as a powerful warding and protection charm.
Another use is to "nail down your property" to protect against foreclosure or being evicted by problem landlords.