I really like the wall climbing aspect of this game, it adds a lot to the fluidity of the game. The headshot multiplier is a nice touch and the gore feedback after deflecting a bullet back or throwing your sword at the snipers head is really satisfying.
I think the boss is a bit too punishing as it shouldn't do that much damage for the area of its attack. Perhaps add more healing options in the boss fight. Maybe add a stun effect to the enemies after you parry them, so that they feel more useful. Then add a parryable attack to the boss to balance the difficulty. The sound effects on the sword are very nice also.
Overall, a really good piece of work. Well done!