Swords have more users however they are more way common in drop rates. (basic demand vs offer)
People are killing oberon / cobra for months before dropping one item falcon or cobra item, and this item needs to be an axe. However people farming winterblade / summer blade will drop at least one per month (or more). A gnome sword is also a common drop from wz 4-6 bosses. So we have a lot of swords in the market while struggling to get a few pieces of the axes.
As I commented, swords used to be more expensive when the axe and sword drop rates were equal (demand vs offer)