runes: why can't use use secondary class as well?

We can all agree that runes are a good thing; they allow a little extra "oompf!" (or a lot, if you don't mind the penalty incurred)
However, why can't we use runes that benefit our secondary class if desired?

I play a Elementalist/Necromancer, and I have equipment that allows me to enjoy better than skill level 12 in my chosen elementalist schools of specialization, yet I have 3 pieces of gear without modifications.

I purchased a minor rune of blood magic, thinking I would give it a slight nudge, and lo and behold, it will not apply to my armor whatsoever...

Is this intentional game design, or an oversight?

Talesin

Just another reason for you to consider when deciding your primary. Puts a cap on the strength of your secondary.

I tried the same thing as a W/E I bought a fire rune to upgrade my fire magic and it didnt work it pissed me off so bad. But ended up helping a person out and sold it for lower price.

It is there for a reason, just like you can't use the armor of your secondary. Else we would all be xx/W.

Runes are class armor specific
(with the exception of the classless Vigor)