Although Vi cannot use her own abilities while charging, she can still use summoner spells.
If Vault Breaker is charged for at least 4 seconds, the channel will cancel and will go on full cooldown. Unlike similar channeled spells such as Varus'Piercing Arrow, Vi is not refunded mana for cancelled attacks.
However, if the channel of Vault Breaker is interrupted in some way (such as with hard crowd control), Vault Breaker instead goes on a short 3 second cooldown and does refund half of the mana cost to Vi.
The initial casting period of the spell counts as a slow, so any form of slow reduction (such as the Swiftness mastery) can lessen the effect of the slow. However, Cleanse does not remove or reduce it.
Unlike most forms of on-hit physical damage, Denting Blows's bonus damage does not apply life steal. This is a special case, perhaps to prevent abuse or for flavor. The triggering attack will still apply life steal.
Denting Blows's bonus damage does not affect structures.