The only use so far that I can find for the Strong Poison is direct application on enemies. I can't find any schematics for "Poison Arrows/Bullets" or "Poison/Envenomed Sword", and just dragging the bottle onto these items don't result in poisoned ammo or weapons.

You can put it in your item area where potions go and use it directly on enemies but it kills them MUCH slower than just stabbing or shooting them would.

For what it's worth, there's an Envenomed Sword, Envenomed Axe and an Envenomed Bow. I don't know how good they are, as my technologists so far have been gunsmiths or pure swordsmiths who were too good to attract evil technologists, but I suspect you can get these by trolling the shops long enough.
There's a trick to that. I think it helps if you leave town before you let a day pass, rather than standing in their shops waiting for their inventories to roll around.

Actually, if you're a screen away and let it roll to the next morning everything refreshes aswell.

Thanks, was wondering.

I should clarify. The reason you'd want to look in shop inventories is for the schematics, not the poison. That you must supply yourself, or gain a follower who learns at least level 1 in the skill.
If you do not take this technological branch yourself, of course, you must get manuals in Tarant if you want to build schematics requiring them.

Actually, I just got schematics for Paralyzing bombs and Paralyzing agents (the directly applied one, that looks like a filled pipette). They require Strong Poison (the bombs also require Stun Grenades, which I have a ton of).

This might be one hell of a thread necromancy, but you can also use strong poison to earn A LOT of money. The ingrediens of one batch costs just about 20 coin but you can sell the resulting batch for about 180 coin