I've noticed that most people keep their food and drinks in containers. Basically, it's near impossible to poison their food/drink, so this skill is quite useless at low ranks (though I do have some inkling how this skills can be very powerful at higher ranks). For now, a poison thief needs a plant to be effective in 'tricking' a person to eat the food. For myself, if I find a berry pie not in my knapsack, I'll be dropping and destroying it.

Anyway, my suggestions is this for the poison path :
1. Keep poison food, poison drink as the same skill. The skill should be poison food/drink.
2. Have a new poison skill as poison/contaminate air. By applying this skill, there is a chance that edible foodstuff/drinks (even within bags and containers) can be poisoned through the poisonous gases that attack them. The number of poisoned items increases with levels and randomly. This makes the poison thief more effective on lower levels and feared at higher levels.

Comments.

.

I look at poison food and poison drink as introductions to the path. And yes, plant is essential. However, I don't find them useless. I used those two skills early on along with plant to find out how well a particular ingredient worked and still use them to test new ingredients. I looked at the population of Galadon as my laboratory and everyone in it a potential lab rat. And while most do carry their food and drink in containers, if you use your noggin a bit, it becomes rather easy to succeed. An example? While most people wouldn't even consider picking up unleavened bread from the street, it's as good as gold to me.

Take a few hints from assassins. Watch your target a bit. Carry a few common food items like berry pies, boar steaks and such. Most people follow the same patterns over and over, relying on the same food sources or relying on the same type of drink container even if they do keep them hidden. My personal favorite are those that use scripts to eat and drink.

Poison thieves are not warriors, you can't run in and spam bash someone to death. Brute force just won't cut it. But, if you consider yourself more of a spy variety, watch your target, take notes, be a thief, you'll have a lot more success and find loads of uses for poison food and drink.