The easiest way to balance would be to copy existing ideas. Reach is powerful ... it's enough to count as an extra +1 to hit, or larger die, or high crit, etc ... in terms of weapon design.
The ability to ignore cover makes sense (it can go around corners), so maybe ignore cover and concealment, the latter being because since you aren't swinging with a rigid weapon, you are more likely to hit a "fuzzy" target. Not superior cover or total concealment, since it's not really going to go through a door, or reach through an arrow slit, and swinging blind is still swinging blind.
Another option would be a conditional damage boost ... close burst weapon attacks or multiple target melee attacks (that don't require two weapons), to go with the idea of swinging it around.
As for the tome, maybe it gives a shield bonus like rod expertise?