The Critical Cannon
Rocket Launcher for Soldier
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=500449232&searchtext=
( + ) Rockets fired are always critical hits.
( - ) 50% slower projectile speed
( - ) Fires two times slower.

The Deflector
Minigun for Heavy
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=229667173&searchtext=

( + ) Bullets destroy rockets and grenades in-flight.
( + ) Accuracy increases as health increases
( - ) Accuracy decreases as health decreases
( - ) 25% slower spin-up time
( - ) 25% damage vulnerability whilst spun-up.

Robotic Fist for Soldier
(Dont have a model atm)
( +/- ) Alt-Fire: Fires a fist-projectile (Just use a rocket) that can be controlled with the mouse. Has -50% projectile speed, and on enemy hit, it stuns them for 5 seconds. Cannot attack whilst using the rocket fist, aside from with the fist itself. Can be controlled as long as wanted, but will stop upon impact. Has a 10 second cooldown
( - ) -50% damage
( - ) No random critical hits

Blacksmith Hammer for Engineer
http://medieval.tf2mods.net/5_2.html (model isnt on the workshop, if i find it i'll edit this and replace it)

( + ) On teammate hit: Grants mini-crits on the teammate for 30 seconds. 10 hits grant full crits for 30 seconds. Each hit resets the mini-crit timer
( + ) On teammate hit: Grants 15 metal to the engineer unless at the max.
( + ) +20% faster repair rate (126 damage repaired per hit rather than the usual 105)
( - ) 50% slower firing speed (1.2 fire rate rather than 0.8 fire rate)
( - ) No random critical hits
( - ) 100% damage penalty

Instruction Scroll for Engineer
http://medieval.tf2mods.net/5_3.html (same as above)

( +/- ) Level 1 sentries shoot fireballs (fireball spell), level 2 sentries shoot fireballs faster, and level 3 shoots fireballs even faster and shoots a ball o' bats.
( +/- ) Level 1 dispensers give teammates -50% less ammo than normal but grants minicrits whilst in range. Level 2 dispensers give teammates -25% less ammo than normal but grants minicrits in a 50% longer dispenser range. Level 3 dispensers give teammates regular amount of ammo and grants minicrits whilst in a 100% longer dispenser range. Gives no metal to the Engineer unless destroyed.
( +/- ) Level 1 teleporters grant minicrits for 15 seconds when exiting, but slows the user by 15%. Level 2 teleporters grant minicrits for 30 seconds when exiting, but slows the user by 10%. Level 3 teleporters grant minicrits for 45 seconds when exiting, but slows the user by 5%.
( HIDDEN ) -50% sentry firing speed (so the spells don't lag the server)

(probably pretty overpowered, but if you can think of a good engineer build pda that has to do with medieval stuff, then please do tell me. same for the hammer, although im pretty sure i made it balanced enough. not sure if i did im not good at all this balancing higgity hoot)

The Bad Trip
Trippy Bombs for Demoman
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2340&searchtext=

( + ) Places laser trip-wire stickies that activate after 0.7 seconds of being attached to a surface.
( + ) When an enemy passes the laser, the stickies detonate.
( +/- ) When destroyed: Explodes, dealing -20% less damage than normal, but +10% explosion radius
( + ) +10% damage
( - ) Cannot manually detonate
( - ) Laser travels until it hits a wall, thus it can easily be detonated from a distance if put in a perculiar place
( - ) Laser is highly visible.

Okay so, heres some items from the Mecha Engineer update. I didn't include the blimp as I knew that was 100% impossible to do without scripting an entirely new thing.

Nailgun for Engineer
(I can't find a suitable model, but yeah)

( + ) On hit: Causes a green, radioactive glow around the opponent, revealing them for 5 seconds. Does not stack.
( ? ) Nail gun, so its like the syringe gun. 10 nails per second, at the speed of 990 hammer units per second. Follows an arched tragectory. 20 ammo loaded rather than the medics usual 40. and carries 150 ammo.
( - ) -15% damage

Plunger Teleporter for Enginerr
(no model smh)
( + ) Can stick to any surface, when used, grants no fall damage for 2 seconds. (Prevents death by fall damage)
( - ) +25% slower recharge time.

EMP grenade for Engineer
(one again no models, probs none for half of these due to them being community update ones)
( +/- ) Causes an electromagnetic pulse in the same radius as a grenade launcher grenade, destroying stickies, sappers and disabling buildings for 4 seconds. Recharges after 20 seconds. Replaces the Pistol.

Upgrade Station for Engineer
(no model once again)
( +/- ) Places a one-use upgrade chest that allows teammates to spend 400 credits on upgrades for their weapon. After 2 minutes, this building is automatically destroyed and cannot be built again for 120 seconds. Money drops upon enemies killed. Enemies can also pick up the credits, although cannot use them unless the enemy also has the Machanist's Chest. Replaces the Dispenser. Acts like an Upgrade Station from MvM. Lose upgrades upon death.

Probably a lot of unbalanced stuff, as im not really good at balancing.

The Tinder Train
Trainthrower for Pyro
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=7185&searchtext=

( +/- ) On Alt-Fire Held: Start the engine of the train, giving the player the Displinary Action buff, leaving a steam trail behind the player and forcing them to go forwards. Each 0.5 seconds takes 2 ammo from the user. Once used, must be used for at least 9 seconds. Cannot attack or switch weapon whilst starting the engine. (When used, it uses the cp_harbor_red_whistle sound effect, reduced a little however so it doesnt just blast the users ears off.)
( - ) No airblast

The Bucaneer's Bomb Bag
Bombing Supplies for Demoman
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=152681860&searchtext=bag

( + ) +25% max primary ammo on wearer
( + ) On death: Drop 5 grenades around your body
( ! ) Explode spectacularly on death
( - ) Replaces Secondary weapon

Lil' Slugger
Weird Creature from the Pond for the Scout
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=522611049&searchtext=

( + ) Throw at your enemies to make them grossed out! (Does no damage to the enemy, instead spooks them for 5 seconds. Reskins the Flying Guillotine)
( - ) No random critical hits
( - ) 20% slower recharge time

The D.I.Y
Rocket Launcher for Soldier
http://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=138229885&searchtext=

( ! ) Hidden: Mini Rockets
( + ) On hit: D.I.Y meter increased by amount of damage, requires 300 damage to fully charge
( + ) On alt-fire with half D.I.Y meter: Shoots 3 rockets in a row at a 90% faster firing speed.
( + ) On alt-fire with full D.I.Y meter: Shoots 3 rockets in a row at a 90% faster firing speed. Always mini-crits.
( - ) -25% blast radius
( - ) -25% damage penalty

Probably needs balancing, im not good at balancing stuff