Oh geez... I don't know if I can detangle all the influences of Errant at this point, since it's a reboot of a comic I initially rebooted a lot in my late teens and early twenties.
Early influences were definitely Bleach and Naruto. Bleach for the big swords and everyone having a unique sword and special magical thing they can do, and for the political aspects and themes of duty, plus gutsy main character with a big sword, but also the modern setting mixed with Fantasy and the irreverent and often absurdist tone, while Naruto supplies a lot more of the art style influence, the vibe of the combat and the focus on teamwork, as well as the theme of redemption. The visual humour is very heavily influenced by the work of Kiyohiko Azuma; both Azumanga Daioh and Yotsubato!/Yotsuba&! I feel like a lot of that is still in there even now.
More recent influences are things like Scott Pilgrim, Undertale, Steven Universe, Homestuck and Netflix She-Ra, with a lot of silly banter, awkward characters, LGBTQ+ themes etc. Plus Errant is generally warmer, more sincere and less snarky than the old comic it reboots, Fan Dan Go, was, which is largely something these works influenced.