For a person or entity:
* -ic: Angelic (adj.) - relating to angels
* -ical: Angelical (adj.) - relating to angels
* -ly: Angelically (adv.) - in a way that resembles an angel
* -hood: Angelhood (n.) - the state of being an angel
* -ism: Angelism (n.) - a belief in angels or their influence
* -ist: Angelist (n.) - a believer in angels
For a quality or concept:
* -ness: Angelness (n.) - the quality of being angelic
* -ation: Angelation (n.) - (archaic) the act of being an angel
Other:
* -ette: Angelite (n.) - (informal) a young or beautiful woman
* -ine: Angeline (n.) - a female name of angelic origin
The best suffix to use will depend on the specific context and meaning you want to convey.