Short of counterspelling, what's best defense against Disjunction?

Anti-Magic Field.

Spellblade? Block Line of Effect?

Yeah, I've got one of those. But Disjunction still has a 1% chance / caster level of dropping an AMF. And those aren't odds I'm in favor of to be honest.

Edit: Partially ninja'ed. What is a spellblade and where do I find it?

Spellblade, if I remember right, is a PrC is... Complete Warrior? It's a fighter-type who has an overriding hatred of magic.

That's an Occult Slayer.
Spellblade is a weapon property from MoF, but it only works on targeted spells, so it doesn't function in this instance.

Is there a Mass Endure Elements spell anywhere?

What edition is Ghostwalk?

3.0

But there is a freely available 3.5 update on WotC (Under web enhancements, IIRC)