I see, so it's not that the combat is necessarily more challenging than other games, but you really have to try hard to avoid dying or there are severe penalties.
Dark Souls' combat is certainly one of its best features. While it's not difficult, timing and precision is key to success with any weapon type (even large heavy weapons that in most games are simply swung haphazardly, are exactly the opposite in
Dark Souls and require some of the best timing). So the game's difficulty come not only in the form of avoiding the penalties of death, but of avoiding death from the start. Enemies can one-hit kill (or at least severely maim) you even well after you've become good at the game and are a high level. Though likewise, you are equally as powerful.
Edit: Sufca, wear whatever the hell you think looks cool, honestly. Unless you're purposefully trying to tank something (in which case you'd put very heavy armor on, like Smough's), it's much more beneficial to wear something light or just what you prefer to look at for hours. So basically, unless you're wearing very heavy armor, tanking isn't a great tactic (and it isn't even great then). Avoiding damage in the first place is key.