Save the game under a new name just before a strong opponent or opponents. Kill them and keep track of the average damage per hit. Use
iZakaroN's SaveEditor to remove all of the skill points from True Shot in that saved game, then re-load and fight the same opponents with the same equipment again. If there is no significant difference between damage done with and without True Shot, then the damage bonus is not being applied. Damage is somewhat random, so you would have to take enough shots to get a good idea of the average and range of damage against particular monsters (who's hit points are also random).
