AllMusic described the band's style as "dark and
metallic hardcore". Heather Weil of Verbicide Magazine stated the band "is one of the handful of metal-influenced hardcore bands that actually know what they’re doing, and how to pull it off". Under the Gun reviews described their sound as "Sending out
posi vibes to kids fighting in the crowd during the band’s last set, Pete screams his sober heart out while Joe Trohman filled in on guitar and Patrick Stump took role of drummer". In reference to their sole studio album, TeethOfTheDevine.com said that "Where most bands in this space use
death and
thrash metal devices to create a sense of heaviness missing in traditional hardcore, Arma Angelus’ thick, angular attack comes from a
rock and roll sense of composition that's every bit as heavy as their metal-infused counterparts. True, elements of Where Sleeplessness is Rest from Nightmares do delve into death metal territory (vocals, tuning), the majority of Arma Angelus’ material pummels to the tune of catchy, head-bashing song structure." Upon their disbandment, the members stated that "the goal of Arma Angelus was to express and stimulate discourse within the punk and hardcore community and to express our distaste for apathy and uncaring, which we felt had become ideals with in the community" They have cited
Damnation A.D. as their biggest influence. ==Band members==