Hello Marina,
If you are really just looking to solo Medusa, I would probably recommend some of the following changes:
Template related:
I would personally drop your Parry, and increase both Tactics and Anatomy to 120. The added damage bonus's will allow you to chain more specials in a row making the kill go a lot quicker. You only need 120 weapon skill, 120 Bushido, and 60 Parry to gain the mana discount on special moves. (This goes for all fights, not just Medusa)
Weapon related: (If possible, use 100% Fire weapons. So you can still hit as hard as possible even when mana vamp'd)
Ornate Axe - You need 55 SSI built into your weapon and suit in order to swing this weapon at 1.25 seconds with 150 stamina. Very hard to achieve if you are not using an assassin suit. It hits like a truck, but is hard to maintain top swing speed. Also it's 2 handed, so potions are a little more of a pain to use. Yes, I'm a potion junkie.
Leafblade - Only need 5 SSI from a turquoise ring or cloak to swing at max speed with 150 stamina. Feint and AI are an awesome combination, but you do give up a lot of damage output. Not the fastest way to kill, but probably the best weapon for staying alive.
(Repond Slayer, HML, HSL, HLA, DI....Medusa doesn't stand a chance)
Longsword - My personal favorite for Medusa. 30 SSI on weapon, 5 SSI on ring, and 180+ stamina for Max swing speed. AI tops out at 189 damage every 1.25 seconds.

This thing cuts through her like you wouldn't believe.
(Repond Slayer, HML, HSL, 30 SSI, DI)
Other:
One last thing to note. If you are using Honor, Repond Slayer, and have 100+ DI on your suit and weapon, Chivalry is Semi-Useless. Enemy of One doesn't add any extra damage output. No need to use remove curse if you are carrying apples with you. And even with my longsword and 120 chiv, I still cap out at 189 damage AI's. When I fight Medusa specifically, I swap out the chivalry for Resist to lessen the effects of some of her spells.
That's all that comes to mind at the moment.
