you can create poisons with alchemy skill. is their anyway to poison your weapons? i cant find anyway to poison npcs.

In Morrowind the negative potions can not be used to poison your weapon, but for some reason alchemists will still buy them from you for a good price.

Without mods, no; these effects are just drinkable debuffs. The best use for them in the vanilla game is to sell them, or if you're just too amazing, use them to debuff your character a bit if you find the game completely easy (though if you're on the PC, you could just use the console).

You can sort of poison your weapons by enchanting a poison cast on strike onto it but it's probably not exactly what you're looking for.