I'm a dual axer too. I haven't chosen any subs yet, but it'll be bard or cleric for me. As a sub-bard I can buff myself and other too.
As a sub-cleric I can heal or even res the others - even if our healer in the party is dead.
I'd say go for heavy armor. IMHO it looks much cooler and you might be able to tank better in it. I dunno really which is better.

In heavy you'll recieve quite less phy. damage but U must be careful with magical damage. However, in a well organized party the healer(s) can save you. At lvl70 there'll be a skill for axers which will add loads of mag. defence. So it's your choice!