This isn't a criticism of these specific poisonous items per se. But, I do want to note that there hasn't been a named poisonous short sword added to the game since the MotU expansion in June of 2012. That's roughly six years.
Thematically and when it comes to their class enhancements, assassin rogues and ninja spy monks are the characters that should have appealing named poisonous weapons. The named poisonous items that have been added to the game since 2012 are weapons that monks and rogues either lack proficiency in or they cannot remain centered while using them, or they cannot apply stacks of ninja poisons while using them because they're not bladed weapons.
Every update for the past the six years, I check release notes to see if there's a poisonous named melee weapon that is usable by assassins and ninja spies. And there isn't...
I suspect that this is an oversight in the named item design because it doesn't track with how other named weapons are designed for this game. For instance, bard's occasionally get named weapons added to the game that deal sonic damage and those are weapons that they're proficient in. And artificers occasionally get weapons added to the game that deal electric damage and those are weapons that they're proficient in. Etc. etc.
But ninja spy monks and assassin rogues haven't gotten a single named poisonous melee weapon for six years that they can use. The highest minimum level poisonous named shortsword is ML 20.