I don't think he is super great at dialog, either, but I like how his cursing is world-specific rather than just reusing what we think of as cursing in our world. He has quite a bit of it in Stormlight Archives (see: https://www.17thshard.com/forum/topic/7204-swearing-in-rosha...) but it doesn't "offend" us here in our world because it is specific to their world.
That's kind of a high fantasy trope. "Blood and ashes!" from Wheel of Time comes to mind. It's like how they like to use different measures of time and distance. "It took him a fortnight to travel all those leagues." Helps take you out of the real world.
It's the ultimate giveaway in the cosmere when someone curses with a different word than used locally, is the sure sign they are far more powerful than they seem.
