The_Last_OneLeft

Okay, I've been thinking. In coppermind.net and in Ars Arcanum, it says that Allomancy is of Preservation, Hemalurgy is of Ruin, and Feruchemy is of both. However why is it that Feruchemy is of both Ruin and Preservation when it creates a End-Neutral result quite literally preserving one's ability for use later. Similarly, it is stated that neither Preservation nor ruin could create, as such Allomancy being a End-Positive means it should be of both Ruin and Preservation.