heres a random napalm soldiers set (secondary and melee subject to pyro as well)

napalm burst: soldier launcher
+on hit: ignites targets for 4 seconds
+on direct hit: the enemy WILL burn till death unless a medic heals them for a solid 5 seconds or picking up a medium or large health kit.

-50% clip size
-10% damage

the shattering sheild: soldier backpack

+25% self damage resist (not just rocket jumping)

+when charged (post 600 damage): reflect all projectiles with a 4 degree diviation from all directions

-20% bannor radius

maximum mania: demo melee CONCEPT

+has a wider hit box innately
+each kill grants increased swing speed and even wider hit boxes (not longer just wider)
+on hit: +10hp

+/- all sword attributes as standard

-on attack: -30% movement speed for 3 seconds
-10% sheild resistances

i know how awkward it is to judge the hitbox of melee weapons so i admit that i can really give any values without knowing how wide something like +500% hit box width would be for example.

valordine accelerant dispenser: sniper primary

+head shots cause the next round to reload +10% faster up to 5 headshots
+headshots cause the target to be damped with gasoline (basicly a much weaker version of the gas passer effect)
+charge level grants next reload buff up to +30%

-charge level multiplier now reduced to x2 rather than x3 at max charge

i figure the downside hits hard enough to justify the upsides here but with the whole knifes edge balence discussion i saw i'm not so sure.

the rampage: heavy melee

+on hit gain +25% swing speed for 4 seconds
+on kill gain a "RAGE" stack
stacks
2: gain "on kill: +40% faster movement speed for 6 seconds"
4: gain "+50% life steal on hit"
6: gain "on kill: 4 seconds of 90% damage resist"

-primary disabled
-20% swap speed IN GENERAL
-33% damage

i admit this needs MAJOR tuning. but this is the best i could think of if heavy went full on berzerk bear man mode

demoman secondary vest: the blasters vest

+50% clip size on primary weapons
+10% damage resist from all sources

if being used with a sword: +100% max overheal
if not being used with a sword: +20% faster primary reload speed and spare primary ammo capasity for every kill up to 4 stacks and disables melee weapons

moon shot: primary soldier launcher

+rockets gain up to +200% blast radius the farther it flies
+50% faster projectile flight speed
+no deatonation damage drop

-33% ammo reserve
-20% damage
-up to 40% blast radius the closer it is to you

meant for artilary soldiers to chip bomb people at a distance

cartigers specal: engi melee

"this is my grandfathers.... he taught me not to hold back!"

+on right click: consume 125 metal and set a building to a boosted state for 10 seconds
sentry boost: temperary wrangler sheild with 40% damage resist and +15% damage
dispenser boost: tripled radius and +50% heal and ammo restock rate
teleboost: emit a larger scale telefrag blast and recharge 15% faster

+on left click: swing a +25% damage +40% range wrench for your old mann!

-no moving buildings
-30% swing speed

eh, it is, but spash/high damage classes (soilders, demos, and kinda pyros, as well as any sniper shot, explosive or not, scout, heavy, pyro) remove your effects instantly in one hit (with very rare cicumstances being the exceptions) or just makes that 50hp vanish like it was never there, making it worse than a scouts medium health kit. if you wanna keep people alive on their last legs you either quick fix flash them, or you crit transmition them. (is that still in the game? i forget) otherwise this really won't help in the frontlines. and again even if it was a quick flash between you and your target, that's worthless when your marked for death post overdosage, you and your target get hit by a well placed rocket, and with all of that encourages bad overly conservative or very passive playstyles. again, this weapon is very poorly designed and far too weak for what you lose in any vanilla medigun, let alone what you get from CTF2W.

the tester: medigun

+50% faster healing rate build up
+60% faster uber charge rate

+uber "overdosage" : releases a small medical wave (2 times the size of a rockets blast radius) healing 50 hp to yourself and allies in range

-25% healthing rate
-marked for death post "overdosage" for 4 seconds

to explain what the main benifit is, basicly if you stay out of combat for longer, the faster a medic will be able to heal you. this benifit cuts the time to reach maximum healing per tick in half. mean while the downside is the opposit of the quick fixes outright increased healing rate