This is an easy but precise way to defeat Shadi. Attack her until you hear a large "clank", which indicates that she has blocked. Then, roll to the side of her. When this is done, most of the time you will be able to get behind her and repeat the attack. You should get to hit her about four times (and possibly up to six times) before she blocks. However, sometimes you may only hit her about two times before she blocks. You must listen for the "clank". Run towards her and do a triple combo. When she does a rage attack, hold [Block] and move backwards. When she ends her combo by raising both swords, charge towards her doing a triple combo attack. Repeat this to win the battle.
When fighting Shadi, she will block. Immediately after blocking she will try to attack. Dodge this attack by rolling to a side and somersault backwards. Let her finish her strikes before going to attack her again. Repeat the process until you win.