Can True Neutral characters wield weapons with a 'Good Effect'?
Can True Neutral characters wield weapons with a 'Good Effect'?
Yes.
Only opposing alignments are a problem (good/evil, law/chaos). Even then, they can still wield them, but suffer a "-1 level" penalty while doing so.
The Cannith Crafting "Good" is usable by anyone, as is Good on current named items.
Older, similar "Good damage" varies. "Holy" can be used by neutral (but evil characters would suffer a negative level), "Pure Good" cannot (without a UMD check).