I am a little unsure about about the abillity to nullify other peoples powers to the extent liegelord's character is able..
When it comes to people like Kyle, Ivy, and Venessa it makes sense because it would be genetic.. by making certian gens dorment he is able to shut there powers down.
As fo Devon and Katsumi this is where it does not make sense...
For Devon, she is a dragon not a human. If he ehere to shut down any gens, it would be her human ones because they are the unnatural gens inside her.. to shut down he draconic gens would have horrifying results.. so what is the differance between say Ivy and Devon? Well Ivy is human, so most humans can not control fire.. that means that the gens that are allowing her to do this are abnormal or mutated where as for Devon this is not the case. Devon is a dragon so the abnormal gens are the ones that aloow here to be human.. shuting down her draconic gens will ultimately erase her!
As for Katsumi his powers have nothing to do with genetics, to shut them down you would have to adress the demon that grant him his power, and that is undoubtedly going to be catastrophic for you! Demons are not lnown for thier cooperation with humans of any kind.. so please explain why your abillities are able to overwhelm a demon that predates your own existance...