interesting though the idea of a modern type hand grenade would be death to serious rp. however i am all for the idea of potions with negative effects you can throw at people.
you can have a red way potion that lights people on fire. azure way potion that creats a blast of air to knock someone down, could rapidly grow poision vines around them and sap their health, crystal way .... i guess you throw it at an ally and it heals them. dark way could drain the targets mana. and blue way could freeze them in place.
but it is an interesting idea to explore grenade like weaponry. though the did have black powder in the oriant and were expirimenting with it in medival times it wasent widley used