ToME: the Tales of Maj'Eyal

If a melee class doesnt have any dex scaling skills , do you need to increase your dex when you level up ?
or Accuracy increasing talents are enough ?

I want to try cursed but I dont know what a good stat build would be =/

Dex can improve defence and accuracy, but generally isn't needed unless you have dex-based skills. With a Cursed in particular you should be concentrating on Str, Con and Will whilst pumping the Accuracy talent to improve your hit rate (though Str boosts accuracy a bit as well).

Str and Dex both contribute directly to Accuracy (your chance of hitting).