Setsuka's battle style is centered around lightning fast and damaging attacks. She was already recognized as one of the fastest characters by the time she debuted SC3. Her combos are fast and deal impressive damage to the point that it can reduce almost half of the opponent's life bar. Her counter hits are impressive too and its difficult for an opponent to recover. Although she has impressive speed and power, some of her her moves and combos are difficult to perform and one single attack without a follow-up attack from Setsuka is weak.
It's the same in Soulcalibur III.
There are some changes in her battle style. Some of her useless attacks from Soul Calibur III are changed to better and damaging moves, an example is her A+K move in which she dashes in SC3 was changed to Ring of Heaven, in which she jumps along with either A or B move in executing a combo, in SC4. She was criticized in this game as her moves were harder to perform than in SC3 like her two signature moves, Sakura Fury Combo and Silver Moon combo, which were easier to perform in the previous game. Also, because of the new damage system, her deadly combos became weaker and one single attack from Setsuka chips a little damage to the opponent's life bar. But her speed increases in this game and can perform faster combos to make up for her weaknesses.
Is the same that Soulcalibur IV.α Patroklos wields a style similar to her. Unlike his master, α Patroklos does not use an umbrella and the sword's scabbard replaces it thus, replacing umbrella-based attacks with his own moves. According to the story mode this is Patroklos' true fighting style, and he used it prior to taking up a shield in honor of his mother. However, when he was 15, Patroklos won his first fighting tournament event during which his father Rothion was still alive and, therefore before Patroklos met Setsuka. This implies he probably used another fighting style (probably the sword and shield) before learning Setsuka's style. Overall, α Patroklos's fighting style can throw off some players who are not familiar with Setsuka's fighting style.