If it is somehow influencing a Pokemon in some form or fashion, odds are that it is an effect.
~Safeguard - It influences Sigilyph, by giving it immunity to Pokemon EX.
~Eviolite - It influences who it's attached to (if Basic), by having it take 20 less damage from attacks.
~Smooth Coat - It influences Cinccino, by (occasionally) protecting it from attack damage.
Shred states that its damage is not affected by any effects on the Defending Pokemon (target). All three of the above are examples of things that affect the damage. Rocky Helmet is not an example of this, because it does not affect the attack's damage.
Really, figuring out rulings dilemma are generally simple...especially in BW-on, where the wording is pretty straightforward and figuring everything out is easy-peasy. Like can you attach a Blend Energy WLFM from the discard with Dynamotor? No, because Blend Energy only provides {C} energy by default. And so on.