In the book Helen is referred to as a "cleric and magic user".
She does have the ability to control insects, snakes, rats, etc. the limits of her ability to control other creatures isn't set out, but it's probably a pretty wide ranging ability.
Her right arm... well, that can be turned into pretty much anything - animate or inanimate. In the book she once turned it into a copy of a weird totem pole with vicious heads biting at each other till they drew blood. And of course, as the living blade - which looks like a bar of light - she can cut through the barriers to worlds and kill any demon of any size or level.
Re: Magic abilities
She does have the ability to control insects, snakes, rats, etc. the limits of her ability to control other creatures isn't set out, but it's probably a pretty wide ranging ability.
Her right arm... well, that can be turned into pretty much anything - animate or inanimate. In the book she once turned it into a copy of a weird totem pole with vicious heads biting at each other till they drew blood. And of course, as the living blade - which looks like a bar of light - she can cut through the barriers to worlds and kill any demon of any size or level.