I really don't know how else anyone can explain Gray beating Invel without using a form of emotional power. It's either PoF, or darkness/negative emotions. Invel spent a couple of panels in ch 498 hyping that latter emotional power. You only need to look at the recent chapter to see what Gray's emotional state is like. The Invel fight also made it clear that Gray wasn't in Natsu's class, and he got a power-up to bridge the gap between the 2.
Emotional power? Invel never hyped anything of that sort...
What Invel said to Gray was that he was slowly being consumed by darkness. This was the result of using
Devil Slaying Magic which was said to eat away at the soul of Demon Slayers. To be honest, this really isn't much different from Dragon Slayers having the ability to dragonize by using
Dragon Slaying Magic.
As for Gray's anger, that is not "Power of Friendship". It was the darkness within him that was slowly erupting. Juvia's "death" may have sped it up but it certainly wasn't PoF which is a random power-up given by the thought of your comrades. Anger is the equivalent of a character's highest potential. In other words, it is fair to say that Gray was going all out in that fight.
I'm not referring to the attack that took Invel out though, I'm referring to the all the base punches with no magic whatsoever that Invel got decimated by and yet he was able to tank Gray's Zeroth Longsword no problem. I think we can both agree that Zeroth Longsword is stronger than Gray's base punches without magic.
Invel didn't get decimated by Gray's punches... He was still in decent condition after being punched 3 times.
Besides a few bruises, he was relatively unharmed. Meanwhile, Gray's
Ice Devil's Zeroth: Longsword actually inflicted major damage on Invel to the point he was bleeding.
I honestly don't get your point here. All this shows is that Gray has good physicals, Invel has good endurance/stamina, and DeS Spells > Base Punches.
Again, you fail to realize that had FDKM been nessecary, it would not have taken only one attack to take Jacob out. Sure Natsu could have taken Jacob out in base with more attacks. But why would he? Wouldn't the most logical thing to do be to try and beat Jacob as quickly as possible? Why would Natsu restrict himself to base for no reason?
The wording was bad on my part, I meant Natsu being frustrated more than angry. Knowing Natsu's character, after being held back for so long against an opponent, I think it's another fair explanation as to why Natsu decided to go all out once he got the opportunity.
That one attack you're talking about didn't even kill Jacob. He came out with minor injuries. So Natsu indeed felt that FDKM was necessary and he was right in that. Besides, if Natsu was truly as strong as you claim, why couldn't he beat Jacob as quickly as possible in Base Form? Is it because he's not strong enough?
Now that is a twist of words just so that you can make your point. It should be clear Natsu was angry at the fact that Jacob was hurting his friends especially since Hiro Mashima emphasizes it in the font of the writing.
Well both these examples aren't equivalent to the END flames around Natsu though. These flames were created from the sudden release of magical power that was triggered when Igneel's power or FDKM was activated. But Natsu had already gone END back where Lucy and Dimaria were and he still retained the flames around him a fair bit later when he encountered Gray. I don't see why the flames, after staying with Natsu for that long, would just disappear for no reason. If this was the same thing as when Natsu activated Igneel's power and FDKM then his END flames would have gone out a long time ago.
They are equivalent. E.N.D's flames are a result of his magic power increasing which is very much the same as Igneel's power and FDKM.
I don't know what you mean by the flames didn't stay with Natsu for that long... It was no longer than a minute or two before it disappeared.
Well I mean, we've already seen firsthand that Jacob does excel in CQC, so his physicality has already proven to be impressive and therefore I think it's reasonable to suggest that his durability would be decent as well. His durability would certainly be higher than Neinhart's, a mage who doesn't even engage in direct combat at all and uses his magic to fight for him.
An increase in MP doesn't nessecarily correlate to an increase in physical stats. I don't know if this is still applicable anymore (I hope it is) but at the very start of the series when Natsu was fighting the two mercenaries in the mansion, they said that many mages spend their efforts improving their magical abilities and as such they neglect their physical strength. I think this is fairly strong evidence that physicality isn't dependent on magical power.
Not everyone who is good at CQC has good physicals. Just take the Garou Knights or Oración Seis for example. Characters like Kama or Racer can fight decently in hand-to-hand combat but the moment they are hit, they're defeated.
I'm not saying Enhanced Neinhart has more durability. I'm saying he would last longer in a fight. Magic power actually plays a more of an important role than people think. The more MP a wizard has, the stronger they can make their attacks just by channeling more magic energy into them. Similarly, the more MP they have, the longer they can last in fight simply by having an increase in endurance/stamina.