Couple of question in relation to foci

1. Can you 'dispell' a power foci? The rules suggest no, since there is no spell on them as such, so the only way to deprieve the mage of said foci would be to either destroy it or to kill the mage.

2. When a mage does enchanting, whether he's aiming to sell the goods off for neyen or to to use it for foci, does any of his astral signature remain? And would the metamagic technique cleansing work on it?

Thanks for your time.

1) No you can't dispell a power focus. In addition to destroying the focus or the magician, you can deprive a magician of his focus by bonding it to yourself.

2) My interpretation of the astral signature rules in the book is that your signature does remain on the goods that you create with Enchanting. I know of no rules in the books for removing such a signature, but would probably make house rules for it in my campaign if any player asked. Here are some references:

IIRC foci deactivate if they leave the user's person. If you can identify the focus you can atke it out simply by disarming the mage. That makes a high incentive for a mage to get a good unarmed combat skill.

can't you attack the focus in astral combat and disrupt it?

Sure you can. And the foci can fight back too. And the foci's owner can add in dice to help. If you're talking about a very high Force Foci, you're potentially taking your life in your hands going this route. Also, disrupting isn't the same as killing it. IIRC, to kill it for good, you have to bring it down to 0 Force, then do some kind of finishing action or it will rebuild over time.

As I've said before, sometimes it's just easier to kill the soft squishy center (ie, the mage's meat body) with bullets than deal with very high force spells, foci, etc. Most mages I've known/seen tend to be more powerful Astrally than Physically.

There was, once upon a time, a metamagic technique known as "Focus Blocking" which allowed you to essentially deactivate another magician's focus with a successful Dispel attempt ('course they could reactivate it later, but it had it's uses).

Yes, you can still attack and destroy astrally active foci, although you can no longer ground spells through them.

Your astral signature should be on the focus originally, but would be "overwritten" by the astral signature of whomever bonds the focus.

For those who play Earthdawn crossovers, you can rule the astral signature remains for references to thread magic, key knowledges, etc.

But does the astral signature remain on expendable spell foci once they've been used?
While on that subject are expendable spell foci active all the time or only when you're using them to cast a spell?

No books right now, but I seem to recall that the Severing Metamagic will serve to deactivate the Focus, or cut the connection between the mage and the Focus. Of course, I also recall that it is pretty weak, as the mage just has to spend an action to re-activate it.