Board Thread:General Discussion/@comment-31371445-20170222233857/@comment-31536324-20180621183537

Simple, the SOUL Modes are the fighting STYLES of each different trait, and the color of the mode is just an indication of what trait it belongs to. The modes are the humans equivalent to Monster Attacks.

SOUL Traits on the other hand I personally feel are two things: a reflection of your core personality trait - who you are at heart - and the means for humans to use magic. Do other traits exist? In the world of Undertale, probably. But here's the question: if these other traits exist, then why were these seven only given prominence? (Other than a meta explanation involving Toby.) I personally think that while other traits might exist, these seven are the only ones that allow humans to use magic (seven souls, seven traits, seven wizards, and a quota of seven needed to break the barrier; it's not wrong to assume that one of each trait is needed to break the barrier rather than seven of one trait). It's not so much that these are the only traits to exist, it's that they're the only ones to allow human magic usage.