Well, from the post I gather you have no weapon, which is obviously standard starting as a newbie. Right, in the game at the moment, there are two types of Rat, regular and \"robust.\" The regular ones are weak and die in a few hits as one would expect, but the robust ones...well, think killer bunny from Holy Grail (one of the best movies ever, hehehe...anyways) You can figure out which are which by right clicking on them and looking at the description pop-up (eye symbol). If it says \"robust\" looking rat, get out of there. I have been playing for about a month now, and I still barely can beat a robust rat, even with two silver falchions.
Also, it does help as a newbie to set the stance initially to defensive so that if the creature attacks and hurts you, you might have enough hp left to run away.
Right, hope this helps
Xirius