I like this idea.Devastating charge. Enemy units can only receive inspiring presence or rally around the flag from friendly units within 6"On the same vein to increase the dread part:
Limiting Inspiring Presence and/or Rally around the flag
Again, not necessarly for every unit or charge dependent, just throwing out random ideas in case somebody from the LAB will get inspired by it
Benefits de spreading out
Artifact of Impending Doom
Enemy units in base contact with the Bearer can't use Inspiring Presence or Rally around the Flag.
This type of item being in the game would help curb deathstars or make those deathstars a bad matchup for a Dread Elf army with this item. And of course this lets the DE player help break castle lists.