Would be nice to make these spells a little more usable. Recommend if possible allowing both spells to be cast on weapons at 1 turn / levels to allow on hit poison/disease respectively. Also to be able to cast both on potions similar to how you can use actual poisons on potions or if this is not feasible make it like bestow curse where you can enchant an item that when equipped diseases/poisons someone.
I would stretch the suggestion towards making it possible with GSF to make these spells have mass/ cloud effects.
Another related idea: the summoned rats of tier 2 still vomit the vanilla contagion, it'd be awesome if they did vomit EFU's contagion.
IMO it would be cooler if these effects weren't so easy to remove (Or identify, in the case of diseases). It kind of cheapens the fear/intimidation factor of someone using these spells if the person just goes "No biggie" *potion glug*