As Ginjo Kuugo has shown, having an inner hollow can drastically alter the appearance of one's Bankai.
's OC Vahan during his fight with former mentor Saitou Izanosuke, revealing for the first time he has gained an inner hollow.
His Zanpakutou functions as a reiatsu and reiryoku vampire, able to absorb an opponents spiritual energy and devour spiritual attacks such as kidou and elemental abilites. Imagine Wanderweiss built into a Zanpakutou but not just limited to affecting fire, or if youre familiar with Naruto, Kisame Hoshigaki's Samehada. Even narrowly dodging the blade can be dangerous as the zanpakutou can devour the reiatsu of nearby opponents. Lastly, everything absorbed is used to empower the wielder.
The eye on the zanpakutou is a visual representation of the inner Hollow's grasp on Vahan's soul.
Vahan's Info page can be found here: [link]
If you like this picture, check out my last deviation:
Vahan © ~Kyero
Bleach © Tite Kubo