Some warriors are incredibly ponderous by nature, or else encumbered by magic that slow them down.
Always Strikes Last
A model with this special rule always strikes last in close combat, regardless of Initiative. If a model with this rule is fighting an enemy with the same ability, the model with the higher Initiative will strike first. If a model has both this rule and, the two cancel out and neither applies so use the model's Initiative.
In addition, if the model's Initiative is lower than their enemy's when it is their turn to attack, they must re-roll successful To Hit rolls when striking in close combat – they move so slowly that the foe can easily deflect their blows.