The stinger weapons are 1H weapons that do elemental damage (pe cloud does air damage). You can sharpen them if you want. However you can't train your accuracy,... for these weapons.
They are useful at times if an enemy has really low resistances for one particular element. I used to give them to my A3 summoning doll to take out the elementals (they have -87 resistance to their opposite element: fire<->water, earth<->air).
If you get lvl 4 alchemy extract you can make permanent potions with holy water so it's definitely worth it hanging on to it.
