User blog comment:IamJakuhoRaikoben/Chapter 473: Red Lightning, Review./@comment-7418318-20160215134501/@comment-7418318-20160215160750

Which still doesn't explain the fundamental flaw: How does the same ability/spell erase both a magic barrier and anti-magic particles?

Furthermore, how could Freed know that Wahl would actually try to dispell the barrier first, instead of just killing Laxus and only then dispelling the Jutsu Shiki? Or rather why didn't Wahl just do that?

At this point Laxus couldn't even get on his feet, so as Wrath pointed out, Wahl could have just walked over to Laxus and bashed his head in, or killed him in a variety of other purely physical ways (neck-snap, stabbing, choking, slashing open and left to out,...).

In this state of mind Wahl should have chosen the most effective way of killing Laxus, free of any sentimentality. Dispelling that barrier was completely useless in regards to killing Laxus since it didn't stop Wahl from moving, didn't damage him in any way (we saw) and didn't seperate him from Laxus... quite the contrary, it boxed the two in together, effectively eliminating the chance of Laxus escaping or outside interference. Which would make it sentimentality/bravado "Look, I can easily dispell your barrier! Hur, hur, go me!"...