Not every SG/Troupe treats all attacks as the same game mechanic once it translates into gameplay. For some roleplayers, a +10 attack by a sword is qualitatively different than a +10 attack by fire, even if the quantity of "+10" is the same. ysmv.
Thanks X!
Hmmm... yeah, the simple fact that it's there doesn't mean it's kosher - it is a wiki, after all, so only subject to peer review at best (and then only if someone bothered to check, and cares to respond - altho' clearly some have).
But the effect seems solidly based on the ReTe guidelines (Base 4 = Base 2 "slightly unnatural movement", +2 for metal), so that much is fine. That only leaves the question of a breakthrough, and that's up to the SG/Troupe - but it's just a predictable application of a well-known effect, so, myself, I'd probably not require a breakthrough - at least not for most Forms (and possibly all - trying to think of an exception, but not coming up with one at the moment*).
(* Side note - THE most important thing for a SG and Troupe to consider in a situation like this is... where can this ruling eventually lead? Are we opening a Pandora's box that we will later regret?
Take the effect to an extreme, apply different Forms, get absurd, try to think outside the box. Try to follow the (il)logic toward some game-breaking ultimate conclusion - and if you can, then think twice.
My immediate here concern would be an unexpected result from a different Form - but not envisioning anything awkward. Any physical attack (inc. Corpus/Animal, and things like wind/hail) are parallel, no problem there. Imagonem... some sparkly effect and a "dimmer" area inside as visual images are partially deflected... meh. Mentem - minds & spirits are "all-or-nothing", no problem there afaics. Vim - same, at least afaic.
Or that it could be easily improved to a "reflect the attack back at the attacker" effect - but I don't ~think~ that would be too easy, at least not accurately.)