we really have to find some kind of style reference for item sprites. item sprites don't have to be masterpieces. they are meant to be iconic. but for that reason they have to be in a similar style.
that means that all weapons should:
-be shown from the same angel
-point in the same direction
-be in the same size scale
-use the same color palette
-use the same shading method
-outline, or no outline, that is the question: Whether 'tis nobler in the world view to avoid it is ok for icons
-show the same level of detail (higher detail level should be reserved for "special" weapons. basic weapons should be kept plain and simple)
the same size scale could be difficult. just imagine the icon of a long spear and a short knive with the same size scale. but at least all weapon sprites of the same category should be size compareable so you can say from the icon that knive A is bigger than knive B and that the battle axe is larger than the hand axe.
oh, by the way, some weapon icons i made some months ago. nothing serious, just some experimentation. it is based on the style of some of the weapon sprites i found on the wiki.

from left to right: saw sword that doesn't look as mean as i would like it to look, rapier that doesn't look as slender as i would like it to look and poison knife that is maybe a little bit overdone.