It took the spell's target a lifetime to acquire everything they know. That's quite a difficult duration to master. Knowing the command word for an item is trivial to learn. Knowing the general process of creating an item, such that finding the lab records is easy and perhaps getting a bonus to translating them, would seem to me to be an evenings work. Learning everything, such that you have a lab-text in your head, would to me seem a waste of a season.
What's the duration of this spell? Because I can barely hold a number 5 digits long in my memory let alone EVERYTHING someone knows. Those memories fade fast. I also think you're going to be ramming into some Hermetic Limits, and the way hermetic magic works (knowing how YOU know a spell does not equate to me knowing a spell, according to the way the rules work).
Thus, I think the guideline is there and is an impractical one to use for a mundane mind, but it exists to let you know where to aim for effect that need to mess with a large portion of someone's memory.
Yes thats what i meant. That you CAN selectively pick up any wanted information.
But that you do NOT automatically get ALL of it just because you can.
Yup. Totally. Thats why i prefer my above version. Then you cant simply vacuum someones head for everything they know, but you CAN get any answer or specific, discrete piece of knowledge that you can come up with to "look" for for the duration of the spell.
Exactly. You've turned someone's mind into a database. You could maybe get answers to any knowledge based questions as if that person were answering the questions, but it's not, IMO, you running around with the entirety of their skill set internalized.
Now that would be an interesting idea for a spell... Not quite sure how to pull it off / if it's even possible, but still. I mean for example, what if you gave such a spell a duration greater than momentary and pulled all of the.. say 'Single Weapon' knowledge from someone's head?
It's in the Jerbiton section. Short version: you should be able to copy Abilities, but can't. No-one knows why. Try some Original Research. You can get some things which are Ability-like but are not Abilites, like the steps to a dance, the words to a song, or the ability to fight as a trained group, but that's as far as Hermetic Magic has yet gone.
OOC? It's for game balance: otherwise the Tremere would just photocopy the minds of their enemies with Rituals at Arcane Range.