see where i'm from, suing isn't something done often, especially in comparison to america where the people tend to sue all the time. so hear me out and understand that my point of view will be vastly different than others you may hear from.
this is where you live, not your landlord (as far as i can tell), you are responsible for your own living environment. unless it is in the contract that the landlord will come and salt your steps when they get icy, it doesn't make much sense to me. he may have assumed that since you know that it is cold, you may have also been more careful on the steps, offering partial sympathy and suggesting you put up as sign or whatever is all that he needs to do.
if you knew that the house was in poor condition, why not take actions to move? did you expect with the conditions of the house that he would also come and salt the steps?
i dunno, to me its alot about common sense, but like i said, i have a different point of view.