Runescape living rock creatures
Let's look at fire giants. They are living beings of molten rock some might say. Now let's ignore the fact that they're still ranging us with their clubs and swords and think of what they could be weak to because of their build. For melee, crush as you are smashing rock. For magic, water because you are cooling them down and effectively removing the heat that gives them rs gold. For ranged, bolts because they are solid metal and thus, potentially capable of penetrating rock.
Another example could be the living rock creatures. Now just because the strikers decide to throw rocks instead of punch, they're resistant to erosion. Raise your hand if that makes sense to you, then explain. A way to deal damage using any combat class would be a great way to allow us the breathe and play how we want to buy runescape gold, rather than just how jagex thinks we should play. This will make the game more colorful with slayers at their tasks using different styles instead of them all wearing and using the exact same set-up like a bunch of boring clones.
If weaknesses are changed to be determined by the foes gear and build then another change needs to be made. The equipment screen shows your strength against classes rather than your current strength as your class. By this I mean you're told how effective you are against your enemy should they be a certain class. The equipment interface needs to be changed to instead tell you how powerful you are using your current weapon. Everyone should already know how the combat triangle works anyway.