Your strength should be good enough. For a boss fight you can also use temporary stat/armour boost potions.
how to defeat stone? - D2:ED topic, so a couple comments about the fortresses do not apply in DKS
Have you checked merchants for better equipment?
You could visit your battle tower to see if you can upgrade some enchantments, etc.
If you are going to be using magic based weapons, you should boost intelligence more, otherwise stick to conventional weapons.