How about an NPC where we can trade Sealed Books of Combat 1 and 7 days for the equivalent Book of Life ?

This would be great for those of us who mostly life skill

and ViceVersa for the combat grinders

Can't see it breaking game mechanics as such.

I have 6x Book of Combat 7 days spare at moment but no life books

Or, and this is just crazy talk, combine them into 1 book so that you get Combat XP, Skill XP, and Life XP all with 1 book.

You can call it a sealed book of experiences.  

I agree, but it will never happen because it's a pearl shop item...