Origins of the word 'Assassins'

I was reading an interesting letter in Dawn yesterday, commenting on Jawed Naqvi's article tracing back the origins of the word Assassins. Accurate or not, it nevertheless gives an interesting version:

A breakaway section of the Fatimids (the followers of Nizam, the 19th Ismaili Imam) was trying to establish a sovereign Ismaili state independent of Egypt. It was after Imam Nizar’s (487 AH - 490 AH) murder that Hassan B. Saba, a staunch adherent, did not accept sovereignty of his brother, Imam Mustaali, who succeeded as 20th head of the sect and escaped to Persia making Persian Ismailis autonomous of Fatimids.

B. Saba’s (1034 - 1124) endeavor was to establish Nizari Ismaili ascendancy in Persia. Saba created a sect from a bunch of die-hard Fedayeens he collected, who after inhaling intoxicant potion of Hashish were prepared to offer lives at the order of the master. These Fedayeens moved freely in adjacent territories targeting their adversaries at will. Their targets were generals and statesmen or any prominent persons who were considered opposing them in achieving their objective. The Nizari sect rose in Persia as a result and its influence extended up to Syria Nusayriyya Mountains where they held many hill forts.

These Fedayeens were eventually named by the Crusaders as Hashishins or Assassins and with this appellation they became part of modern lexicon.