the face of pyrhuss

[Βελισάριος]

No we don't... Where do you think the word "assassin" comes from.

Yes, we do.
Assassin comes from that word, but there is more than one way for any one word to enter a language's vocabulary from another language.

In the one case, it was assimilated and given a (slightly) different, yet similar meaning: assassin.
On the other hand, Hashishin is a "barbarised" version of the original term, used closest in meaning to the original (i.e. the Hashashin, which is ironically listed on Wikipedia under history of terrorism... new for me, but let's not get into that). Only it was adapted to English, using an already existent word, which in this case is hashish. Thence, Hashishin.

And, finally, a word can be entirely "stolen" from another language, which is why they are also referred to as Hashshashin.

I'll learn my Arabic if you learn your English.
The Professor has spoken.