I took my cue from his own fantasies and read him old Tarzan comics, rich in combat and bright with flashing knives.
the kind of sentences confused me.
To my knowledge, you need a "which are" before "rich" if the "rich in combat and bright with flashing knives" refers to "comics", otherwise the "rich in combat...." refers to "I". But, i've read this kind of sentences from time to time.
It's obviously fine with 'which are', but it works without it- I wouldn't interpret it as describing the subject 'I'.