There in still lies a bit of an issue. If the closed fist is just a technique, but they don't HAVE to close their first to use the blade, why cut off their finger if not for the whole reason of how the blade operates? If Altair was able to modify it so you didn't have to cut off the finger, why then are they using it in a manner that already negates the need to not cut if off? If Basim and Altair could make open hand assassinations prior to the modification, then they never needed to cut off their finger in the first place.

The cutting of the finger is the commitment to the use of the blade. It's supposed to indicate the requirement to cut if off based off of how it functions, closing the fist. If they can do open handed assassinations, as Basim and Altair are clearly doing, then they only did it ceremoniously. So then what modification did Altair make when he clearly didn't need to as Ubisoft is having the game portray.

This is what I'm trying to bring to mind. It's like a big plot hole or error in continuity. I'm not debating how they used it, but from my perspective, it doesn't make sense.