Ariich has released Sci Fi but escapes and I die

Hint 1 of 5:

You must kill Ariich. Remember that it is a parasite.

Hint 2 of 5:

Kill the body it lives on and it will die.

Hint 3 of 5:

You must kill the Hassk body without moving.

Hint 4 of 5:

Use the sacrificial knife you got from Sci Fi.

Hint 5 of 5:

THROW the sacrificial knife at Hassk.