Just to clarify some potential ambiguities:The Finger can only channel Sith magick, meaning that there must first be a source of it available for use. The advantage this gives to the user is that once collected, this Sith magick can be used in whatever way the wielder wishes, provided there is enough energy available. For example, Han Solo could use the Finger to turn himself invisible, providing that there was a Sith sorcerer nearby to draw the power from. If there was no sorcerer nearby, then the Finger is a nice fashion accessory.
More power can be drawn from a willing sorcerer than an unwilling one.
If used by a Sith sorcerer, the Finger will amplify the power of the magick.
If an All user uses the Finger, that person may provide All power to the Finger. This power must be given willingly, the Finger can not draw it from an Al user. Once given , the Finger can then combine the All power with Sith magick (if there is a sorcerer nearby, remember) and create an energy much more powerful than either of the two sources individually. The wielder must be strong enough to use this power or else runs the risk of getting fried.
The Finger itself has no sentience. It is a device created by the Sith some time in the future. It is not known how or why, but the Finger appeared in the far past of the Sith and the ancient spirit of the Axis was placed inside of it. Axis was a legendary servant of the gods, and in the mythology was always sent to do the “dirty work”.