Helichrysum is another one of those amazing and healing aromatherapy essential oils. There are different species besides Helichrysum italcum, and you should also consider the country of origin when purchasing an oil. This post is about the absolute, which is for perfumery, not aromatherapy. Absolutes are solvent extracted, so they're generally not used for aromatherapeutic applications. While you can use the essential oil in perfumes, the absolute is usually cheaper. If you have the essential oil and want to use it for its fragrance, keep in mind that other species can have different odor profiles.
Known as immortelle or everlasting, the absolute catches your attention with it's poetic name before you even open the bottle. The scent is sweet and honey-like, with tobacco and hay nuances. Arctander mentions it's fixative effect (though also mentioning you're unlikely to use it enough to really work as a fixative), as well as it's value in "rounding off and 'bouquetting' a fragrance which may need life and naturalness."
Consider adding immortelle to bring some sweetness to a blend. I can picture using it in a meadow-type fragrance, along with some herbal and floral essences. I would reserve this material for perfumery, since it might not mix into whatever else it is you make. When you do use it for perfumes, you might need to heat it up gently (warm/hot water bath) before and/or after adding it to your alcohol or oil. This method is useful to keep in mind with other thick materials. The essential oil will blend easier into different bases, so if you have the money for a helichrysum soap or want to add it to a lotion, the EO is a better choice.
Similar odors (per Arctander):
Broom or Genet Absolute (Spartium junceum)
German Chamomile (Matricaria chamomilla)
Roman Chamomile (Anthemis nobilis)
Flouve Absolute (Anthoxanthum Odoratum)
Hay Absolute (Foin coupe)