Don't take my word on it but Shirou's weapons would count as magically conjured. HOWEVER, he can also use his powers to enhance already existing weapons, like making a knife more resistant, better balanced so it's easier to use, and capable of cutting even through other metals.

Nooot sure if the enhancing thing could be removed by Shifting, though.

Probably not very helpful but just wanted to add that. If the enhancing isn't affected by shifting even if his conjured weapons don't work he could very well enhance the ones people have already.