Guild Wars 2

I’ve been wondering, is it possible to transmute two armours of different Armour Classes? For example: Transmuting a light armour and a medium armour so that it has the stats of the medium and the appearance of the light.

No.
as far as i know they both have to be the same type.

That’s a shame. Oh well, thank you for answering my question.

Yup same armor class.. Same with weapons.

Can’t do Greatsword -> Longsword

If you’re trying to fine some cooler medium armour looks.. there are very few. Good luck. Medium got the coolness shaft it seems.