Arnold had two brothers, Panyit, who became infamous for his violent actions and plunderings against neighboring estates in the 1250s and 60s, and Keled I, the ancestor of the Hahóti noble family.

Then he was a supporter of Duke Béla, who had long opposed his father, King Andrew II's "useless and superfluous perpetual grants".

[3] In this capacity, Arnold was entrusted to lead that investigation committee in 1236–1237, which supervised and sometimes overruled previous land grants occurred in the southwestern part of Transdanubia (primarily Zala County).

[6] It is possible that after the catastrophic battle, Arnold joined the entourage of Béla IV, who narrowly escaped from the battlefield and fled to Dalmatia.

Perhaps Arnold was appointed Palatine on a temporary basis, when Béla waited in exile until the withdrawal of all Mongol forces, and later re-establishment of the royal court in Hungary.