Page 250 of Demon says:
The dice pool and effects of an Interlock should be based on the two Embeds. Use the Attribute from one and the skill from another, or if the appropriate dice pool remains the same, base the game mechanics of the Interlock on a mixture of the two. Try not to make either of the powers redundant in the Cipher.
So the rolled Attribute must come from one of the Embeds. I like this because it keeps the Interlock focused on the right area. (E.g. I had designed an interlock that was far more similr to one key than the other, and when it was time to sort out the attibutes I found it didn't make sense, so I rewrote it slightly, and ended up with a more even and overall more satisfying (in the context of the Cipher and its final secret) result.)
Page 156 says:
... These powers are not Embeds, and so can involve Aether expenditures and non-Finesse Attributes.
Page 124 (sidebar) says:
Embeds Dice Pool: Since they rely on careful manipulation of natural and supernatural laws, Embeds always use a Finesse Attribute (Dexterity, Wits and Manipulation) + a Skill (any type). Unskilled penalties do not apply.
- doesn't have to use Finesse Attribute,
- but it does have to use a Attribute from one of it's key Embeds,
- and all Embed Attributes are Finesse Attributes.
Has this been explained or errata'd?
Maybe a house rule like, "it can use the Power or Resistance from the same Category as Embed's Finesses Attribute," would work?