Iron's Complex Trait, -3 points or -6?

Pg. 392:

Trait Limitations
A trait limitation indicates that one trait in the device requires another external trait in order for the main trait to work properly—ammunition, a power supply, a special key. A trait limitation reduces the cost of the technology by three points.

Pg. 393

Complex -3 pts
Characters without the Iron Trained trait may not operate iron at all—even if they have a crucis.
Technological Traits: Trait Limitation

Page 546:

Complex Tt -6 pts
Characters without the Iron Trained trait may not operate iron at all—even if they have a crucis.
Technological Traits: Trait Limitation

Since two of the three passages seem to agree it should be -3 points, I’ve gone with that in building the Hussars and assumed page 546 was a missprint – but then I ran across this in Luke’s post on Index 3 and Index 6 Iron:

Crucis and Iron – Requires the Crucis (or Illegal Crucis) and Iron Trained traits. (2x Trait Limitation, -6 pts)

So is -6 actually correct, because “requires Corvus and Crucis” and “requires Iron Trained” (or “requires Hussar Trained”) count as two separate Trait Limitations at -3 pts each?

Or is -3 correct, because “Iron Trained” (or “Hussar Trained”) requires “Corvus and Crucis” by definition and therefore they aren’t really two separate restrictions at all?