Could be improved.
I'll give you credit for the graphics; they were pretty decent and well drawn. Animation was okay-ish too, could be made a little more interesting though.
However, the plot is severely lacking. It just reeks of deus ex machina.
- Convenient brick thing to jump up onto when getting into the building. What sort of deranged designer came up with a jutting brick of all things?
- What sort of weirdo parades around with a strange elaborate tattoo on their head? Granted, it may be some occult symbolism, but furthermore, why did the assassin ( I take it he's one) get a letter with nothing but a symbol to target a person? Generally speaking, people give more explicit instructions.
- If this assassin guy is so strong and stuff, capable of hurling hulking brutes out of windows, and bisecting TWO ARMORED people practically instantaneously in midair, how in the world was his attack parried by a fairly frail-looking person?
- Said frail person proceeds to beat up assassin. Barehanded. Assassin does nothing but stand there and get beaten around. No, the weapons on the floor are of little consequence. No, he doesn't happen to have any other weapons on him, as assassins obviously only use a sword, and his daggers have all been thrown away. /sarcasm
- Person is locked up in a dungeon. With nothing but manacles around his hands, nothing binding him to the wall, or even his legs. Extremely convenient sword on the wall once more. I mean, seriously, which idiot keeps swords in the dungeon?
- Execution of prisoner carried out by who i presume to be the ruler/whatever of the place. No executioner. Pretty cool if you happen to want to assassinate this person with a handy sword you found lying around. /sarcasm
Motif of Death also could have had some more usage, it was promising, but completely botched. (Why'd he have to run to the same place twice? At least a quick cutscene of the souls of the other few people that were killed.) But I won't fault you too much on this, since it's probably difficult to get clear imagery for it.
All in all, I think the problem lies with the plot. Deus ex machina man, if you have to commit it, don't commit it more than ONCE.