Standard Poison Potion not affected by the poison effectiveness modifier from daggers and spears

Standard "Poison Potions" aren't affected by the poison effectiveness modifier from daggers and spears, (possibly not affected by negative modifier from staff and bludgeon?) - so they do less damage to Stinging Poison, which IS affected by the modifier & costs about 50% less to craft.

(without any weapon modifier - for example when using a longbow)
Poison Potion: 3-7 physical every 2 seconds for 10 seconds (15-35 damage max)
Stinging Poison: 2-5 physical every 2 seconds for 10 seconds (10-25 damage max)

(with +50% Poison Effectiveness bonus from a dagger)
Poison Potion: 3-7 physical every 2 seconds for 10 seconds (15-35 damage max)
Stinging Poison: 3-8 physical every 2 seconds for 10 seconds (15-40 damage max)

NPC bought components crafting cost:
110 gold: Poison Potions x3: 3 flasks (30 gold), 8 nightshade (32 gold) , 8 corpse wax (48 gold)
50 gold: Stinging Poison x3: 3 flasks (30 gold), 5 nightshade (20 gold)