You could say you miss something.You can improve your combat everytime you gain a level. Gaining levels is acquired by gain experience points, which you get to fullfill quests and slay monsters and other enemies. Large monsters, such as ghouls, will give your more xp. For quests, well there is not only the mainquest, but also several sidequests. One of the sidequests is to do contracts. You find contracts on noticeboards. The contracts is mostly by slaying some monsters and acquire the ingredients. Next to that there are also some trophies you can obtain. A trophy is to slay an unique monsters, such as ozzrel in the outskirts.And there are several persons which can give you a quest.It is not only about potions and the correct combatstyle, but also to develop your character and using oils and bombs.In the case how to use potions, oils and bombs, look in formulas in the menu and also to monsters and ingredients. You can find all the information there.Use the J button where you access your journal and you will see also tabs to monsters, formulas, ingredients, glossary and such. If you are unable to find the herbs, then you probably don't have an ingredient entry yet. Those entries are obtained by reading books.You have to read alot of books and scrolls to obtain information about monsters, ingredients, formula's and glossary. Books and scrolls can be obtained by buying it from a bookseller, some merchants and alchemists. You can also find them at random places, most of the time in shelves, cabinets or trunks.For example; in some houses in the temple quarter. And sometimes you are rewarded with a book or scroll by a npc if you do something for them or with a certain deciscion.About that plant thing you mention; is that the one near the clay pits or near gramps house? and is it red and purple?If so, then you have just found an unique archespore called coccacidium. A real nasty thing. Vincent is very interested in the remains of it.