BSN why you no?
Assuming we ignore the fact that he is a dwarf and can work safely with lyrium while mages and mundanes can't its not something especial to none-mages. Mages can pick that up too where as mundanes can't do what mages can with lyrium.
The enchanter in Awakening was not a tranquil and could handle enchantment.
I've stated before in the past that I see no reason why regular mages and mundanes can't work with lyrium. However, I also recognize that it's extremely dangerous to work with, even for dwarves. They can't inhale it, get in the blood or their eyes or such.
If someone has been properly trained and takes proper precautions, I think anyone can work with lyrium. Tranquil and dwarves simply have the easiest time of it, the dwarves because of their resistance, and the tranquil...well, I suppose it has to do by being cut off from the Fade. That or their inability to get distracted from the task at hand.
Could Blood Magic be used to enchant? It can be used in replace of Lyrium for a variety of purposes
I doubt it. Not unless you can form it into a rune and then fold that rune into any piece of weapon or armor. And since blood is a liquid....not likely.