Quote:
You'll have to make use of a completely new weapon for this battle, and while the Blade of the Gods has a number of unique moves they're almost entirely useless. The attacks (such as Zeus' Gift and Athena's Gift) are too slow to be effective, and they'll leave you totally vulnerable to Ares' attacks.
In fact, almost every one of the attacks at your disposal is pretty useless, and unfortunately you don't have your magic powers to fall back on. The one attack that is effective is the CIRCLE button combo. Start the fight by playing defensively, blocking his sword swipes. You can block all but one of his normal attacks, so as long as you're patient you'll be rewarded with an opportunity to counter-attack. Wait for Ares to finish his combo (usually ends with either an air launcher attack, or an attack from his back-mounted spires) and then counter with your own combo using the CIRCLE button. Just repeating this pattern alone should be enough to defeat Ares.
Occasionally, Ares will start glowing and teleport away. When he does this, stand completely still in the center of the arena. Ares will summon four spires (sometimes fewer) that come out from the ground and quickly smash together in the center. If you wait for the spires to form, you can immediately roll sideways and shoulder charge away to move out of the blast the spires create when they smash together, effectively dodging the attack. After this, you can run up to Ares to let out an attack or two before blocking his combos and countering with your own.
Ares' sword will sometimes glow bright orange as you're attacking him. This'll let you know that he's about to engage a weapon clash. When both your weapons clash, mash the CIRCLE button—if you succeed (it's not hard) you'll deal a massive amount of damage to Ares, and he'll be left stunned afterwards for a quick follow-up combo. Repeat this pattern of defend and attack and Ares, the great God of War, will die at your sweaty hands.
Video of it