The Demoknight is in a really awkward place within TF2, despite being the closest thing TF2 has to a tenth class with its own mobility, strengths, and weaknesses. The main issue with this is Demoknights were never as good as their sticky launcher brethren at dealing large amounts of damage, taking out fortified barricades, and overall keeping the enemy team suppressed. However in exchange for this loss of firepower the Demoknight gets a close range, high risk high reward charge mechanic that allows him to get to places no Demoman could ever dream of getting to. At least he could until the recent nerf to the only viable option the Demoknight had in its arsenal.
The core flaw in Demoknight was its inability to be useful outside of pub play. The Chargin Targe is good at annoying pyros who rely on combo attacks and for being a bulky grenade spammer, but how often do you see targe Demos actually go for cool sword kills? The splendid screen offers less tanking ability in exchange for damage, which is good in theory but not so great when the only way you can deal that damage is if your enemy is being immensely predictable and is completely unaware of his attackers. The Booties should never be considered at all, because sacrificing your primary weapon without a sticky launcher is a death sentence against players who can grasp the concept of walking away from the slow melee man and shooting him.
Then one day we Demoknights get the tide turner, a weapon that frees knights from the chains of pub play, something that allows it to be its own class, and allows you to do things a sticky Demo could only dream of. With turning capabilities allowing you to kill players who actually know how to play the game, and the charge refill allowing you to actually be rewarded for the risks you take and the kills you earn, the tide turner was Exactly what the Demoknight needed to actually be viable, not as a Demoman but as his own class.
The recent nerfs however have taken Demoknight back to the mediocrity of the other shields. I am not talking about the 75% charge refill thing, mainly because I find that part well thought out because any Demoknight who knows what they are doing would admit that the Claidheamh mor was the best Demoknight sword in the game. No, the fact that even the dopiest of SMG snipers can stop your charge cold in its tracks. This nerf was terribly thought out and restricting full recharge to the booties and claid would have been enough to satisfy those frustrated with this weapon. Lowering the resistances or granting a shortstop like knockback increase would have made it more counterable than it already was without making Demoknights into a complete joke.
Valve cared enough about Demoman to revert a poorly thought out nerf until they came up with a better one, I don’t see why Demoknights are not entitled to the same treatment.