So, started a battle and thought let's try the oil of sharpness (not acuteness) which makes weapon +3 for 1 hour.
Opened inventory, moved oil to quick access slot, closed character sheet, clicked on oil.
Message: waiting for 1 minute
Everyone hung around for 1 minute while the ranger rubbed oil on his bow.
Then we all started fighting again :)
Those vampires are so understanding.