I would recommend reading u/QVCatullus 's comment on general use of poison weapons. Additionally, his suggestion of reading the text "Greek Fire, Poison Arrows & Scorpion Bombs: Biological and Chemical Warfare in the Ancient World," would not be without its benefits as well as Kim Coleman's book "A History of Chemical Warfare".

It may come as no surprise that humans have been poisoning our weapons for thousands of years, with Greek armies using snake venom on arrows as a way to increase effectiveness against enemies and South American tribes such as the Noanamá Chocó using the poison of the aptly named Poison Dart Frog to make their weapons more lethal. Firearms, as used in their oldest, but still resembling modern form, were first introduced to Europe circa 1380. As human nature would lead us to do, European armorers would attempt to continue this trend and incorporate poison into the newly introduced weapons. While I cannot find any sources that directly mention widespread use, Leonardo da Vinci did, in fact, have schematics in one of his "notebooks" for cannon and rifle shells that were packed with powdered Arsenic and sulfur to be fired at ships in an attempt to breach the hull or galley with a noxious gas that would choke out crewmen. (Da Vinci's chemical weapons are outlined more clearly in the Kim Coleman book cited above.) These shells were the first recorded use of biological weaponry outside of the aforementioned stabbing weapons coated with toxins. These shells were also the inspiration of the Strasbourg Agreement that you ask of in the original post.

To continue past the 1675 agreement, bullets did not travel nearly as fast as they currently do before the invention of smokeless powder in 1884 and proper gas sealing years before. Prior to these inventions, bullets went slow enough that they could be made of pure lead rather than a jacketed bullet without melting and fouling the rifling or barrel of a firearm.