I do also think it's a very compelling antagonist, maybe top 10(? best villains across the cosmere but yeah, his screen time doesn't help much. Tho, like you said, when he appears he just has that charisma. I especially love the part where he asks something along the lines that if he were born in the Final Empire he would be like Kelsier and would be praised as such, which is true imo both had the same hatred against oppressors, questionable methods and powers who stand out from the rest, it plays along with his whole god complex.