Ok please tell me how my single class Sorcerer can take a feat and use Cleave.
I thought this was in reference to valor bards and this looks like moving the goal post. I don't think you've demonstrated why sorcerers need weapon mastery at all or cleave in particular, but the sorcerer needs the martial weapon training feat before 9th level and can use a training area in their bastion to gain the weapon mastery trait of a great axe for cleave with the empower option.
This costs one feat and downtime before the adventure.
There is no feat or combation of feats that will allow this for a Wizard, Sorcerer, Warlock or Druid to use Cleave.
These classes don't need cleave and giving them a free weapon mastery doesn't change their weapon proficiencies. You're incorrect though.
A druid with the warden primal order has proficiency in martial weapons and can take the weapon mastery feat at 4th level for cleave.
A warlock with pact of the blade is proficient in that weapon, which can be a battle axe, to qualify for the weapon master feat.
Any of them can take the martial weapon training feat and then the weapon master feat for +2 worth of ability score increase and that weapon mastery.
Cleave is still moving the goal post from weapon mastery to specific weapon mastery. Any of them can spend one feat for weapon mastery within their weapon proficiencies.
On the other hand any martial could use take an Origin feat and use both Green Flame Blade and Cleave and Eldritch Knights can do it without any feat.
There's nothing wrong with that. Just because a martial class has an option doesn't mean a full caster needs the same option. Full casters have plenty of options not available to martial characters. Using that option removes extra attack for most of them, though, so the desire to give free stuff to casters in order to match an unlikely option for martials makes even less sense.
It's also something you're incorrect about. Rogues cannot cleave either. Weapon mastery isn't weapon proficiency.
Several spellcasters can take the weapon mastery feat and also apply it to green-flame blade, however.
Someone else brought up Green Flame Blade and Cleave, claiming that casters could already do this just by getting the Green Flame Blade Cantrip.
They weren't wrong. Cleave attacks a second target in the attack and green-flame blade damages a second target in the attack. Green-flame blade is better, however, because it doesn't require a second attack roll and typically does more damage unless the cleave can stack some bonus damage on the attack.
Vicious mockery also replicates sap. Ray of frost replicates slow. Thorn whip does pull instead of push.
Weapon masteries don't replicate chill touch preventing healing or mind sliver inflicting a save penalty, or many other cantrip options.
That is how this got started and I pointed out at the time they need a feat too, now I realize they can't even do it with the feat.
Only if you push the goal posts cherry picking cleave because of weapon proficiencies. But I did demonstrate otherwise above.
Mastery should not be uniquely a martial toy. They should be available to everyone I think. Less of them for casters than non-casters.
Hard disagree. Weapon mastery is a martial trait with no good reason to give it to full casters other than your desire for it.
I am not comparing EKs to full casters, you or other people are. All I am saying is they are the only character that can use Green Flame Blade and Cleave (and they are).
Which is meaningless outside of that comparison. Just because it's harder to do something EK's can do easily isn't a reason to give that ability to everyone else.
I don't see why we need to compare classes and why we need to say this class should not have this cool thing?
That's like saying all martials should cast wish because wizards can and fighters can't. Just because something exists doesn't make you entitled to it.
There is only one question that matters - would the game be more fun and more cool if full casters and Monks had one weapon mastery. I think the answer is yes and that is why I think they should have it. The fact that other classes have it too is kind of irrelevant.
Hard disagree. It becomes less fun for players who see their toys being given away. It's the whole basis for protecting iconic spells for spellcasters. That same protection goes the other way.