Gray has shown to endure a sword stab and slash through his torso when he fought and eventually defeated Lyon on Galuna Island.
Laxus has displayed physical durability of greater magnitude when he took an explosion bullet head-on from Hades, which was powerful enough to blow through the reinforced armour of the hull of Grimoire Heart's battleship,
without any magic power in his body.
For reference, when a mage as skilled and experienced as Makarov suddenly got all his magic power depleted, he couldn't muster even the energy to stand and eventually went into a comatose state.
What Laxus accomplished in that instance, with purely his physical durability, was unheard of.
I don't know why we are discussing about durability when you have already seemingly made up your mind that Brandish can simply enlarge Laxus' organs till the point where they explode, effectively bypassing conventional durability. Your argument is all over the place. You were skeptical that Laxus can tank a knife slash, because according to you, he has never shown to do so. Yet the feat above, and fighting toe-to-toe with Assault Wall who literally absorbs lightning, while being severely afflicted with his fatal illness, is enough evidence to suggest some knife slashes are hardly going to do Laxus in.
On the other hand, you are so certain that Brandish can enlarge Laxus' organs, when she has never shown to do so. That is either double standards, or you are inclined to give Brandish some massive benefit of doubt in her favour.
Brandish couldn't touch Neinhart after he was enchanted, and neither could she alter the size of Natsu's tumour when he was comatose.
She could, however, do so before Natsu's END side was awakened. During that time Natsu regarded Brandish as an ally, and completely let his guard down against her. In addition, that was not during the midst of a battle. I doubt Laxus would adopt the same mindset as Natsu did then. Furthermore, Brandish's character has never been portrayed with the malicious personality and fighting style of bursting her foe's organs, that Dimaria claimed. Statements made by characters in the series can often be erroneous.
Larcade was stated to be a trump card against Acnologia. That S-Class monster in the GMG's Pandemonium was stated to be on par with Jura. Jura was stated to be on par with Gildarts. Bluenote's Black Hole was stated to be capable of sucking anything in. Bottom line? Don't listen to empty statements made by characters, when they are not backed up by any feats of substance. At the end of the day, there are too many variables that have to be met in Brandish's favour before Laxus finds himself falling vulnerable to Brandish's magic.
