I don't really play lockdown because I find it frustrating getting killed by people that are better than me, or just lucky, or any of that... but I play TF2 all the time even though I get killed and it struck me that TF2 has classes that don't actually do fighting stuff, like Medic and Engineer, but that lockdown doesn't.
Buffs for guardian
Refocus guardian to be more medic like, a sort of moving checkpoint for the team. To do this, buff their shield-
+non-guardian team mates have faster ability recharge (cloak/booster)
+healing is at a decent rate for team members
+mild attack/speed/defense buffs for team members.
+shield doesn't take damage for team mates
-cannot walk while shielding, or even slower move speed
Instead of chaotically running around fighting, strikers would flock to these players. They'd have to. Their most important asset, their shield, would be a vital aspect of game play... but if you only run guardians, shields get broken easily as they already do, don't get charged by other guardians, and the team falls apart.
New class: Technician
Each team gets 4-5 destroy-able energy sentries. These sentries start behind your lines around the health pads, where they can shoot at potential spawn campers.
Technician comm relay:
+global ctr very high
-global attack speed and damage down low
+same health bonus as recon
+can pick up and move sentries so that they can defend points/areas, via 'attack'
-only the 4-5 sentries can exist at a time and are shared between all techs.
-sentries cannot be placed in spawn, except on their pads
+can heal damaged sentries by holding defend next to them
+when sentries are destroyed, can rebuild sentries on their spawn pads as if healing
The purpose of this is to maintain territory. If team A has a sentry on the point it's much harder
It's funny because I've been pushing for both a technician class and a scout class for a while.
One thing about lockdown is that what makes every class unique is its shield, and then the shield alters a few stats to encourage how to play that class. As such, each new class we implement needs a shield that is key to its gameplay. We shouldn't lock players into roles... Instead we should give them a base to work with and let them adapt to it.
I have two thoughts on this situation - A) class variety is entirely dependent on gear right now so it's hard to specialize and B) when you do specialize more often than not your specialty isn't really valid.
Thus, I would recommend an "alt" shield for each class. When you walk over a class shield swapper you'll change to the main shield, but if you press shield on the pad you'll swap to the "alt" shield.
Alternative shields would specialize in a different direction from standard shields. All shield penalties would remain the same but actual shield functionality would change:
Here's what each set would entail:
This shield would act similar to the current guardian shield. It would simply be adjusted to only take damage from attacks once per attack (ie, heavy sword swing only hurts the shield once instead of for every teammate under the shield). The shield would also gain its own "sonic mode".
This shield would have half status resistances but heal players inside for 5% of their total health instead of half a pip per second. Also recharges friendly shields at the same rate of a seraphynx shield and starts the shield regeneration process 1 second faster when under a guardian shield.
Similar to the current recon cloak. Makes the user invisible but marks enemies once, and then second mark removes all defense. However, while under cloak for more than 1 second, the player gains MSI: low.
This cloak would be similar but not the same as the current cloak. It still turns the user invisible, and the first mark still warns enemies of your presence, but instead of applying a deathmark you would steal half of the enemy's shield and set their dash timer to 3 seconds.
Same as current striker boost. Makes the player move quickly for 3 seconds while in use and recharges instantly.
Instead of a constant speed, this boost would make the player move slower at full shield health and faster at lower shield health. This boost has 5 seconds of boost instead of 3 seconds, and recharges itself in 1 second intervals every second after it is depleted (with an initial 2 second cooldown period).
Bam, different playstyles that switch up the game a bit.
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As for your technician concept, I would take it a different route. Guardians are currently our "stand on points, hold down points" class type. Adding another one of those into the mix won't really help too much. Instead, I would recommend something more centered around using their shield.
What I've suggested in the past is that technician shields would be a short range shock burst. However, if you stand still for a few seconds you'll start constructing a mecha knight to move along with you! The building process should add up to about 7-10 seconds. Once built, your short range shock burst can heal friendly mecha knights, and if you focus it on the enemy's mecha knights long enough it would hack them to your side! Additionally if you "heal" a friendly mecha knight over its max health, it'll get attack and defense buffs, but like orbs only for a limited time. Mecha knights would be built with random statuses on them, have no limit on how many you can build, and would follow the nearest technician until it found an enemy to fight. They would act like tier appropriate mecha knights.
Instead of having another "bunker down and hold the point" class, we can have a mob class. A full team of technicians won't be all that great VS a guardian, however if a striker runs into a technician they'll run into some pretty serious trouble unless they keep their distance.
On top of that, if I were to make my scout class be a thing, they'd essentially be a recon minus the cloak, and instead their "cloak field" would give all friendlies within the radius MSI: maximum. This sets the speed to max, it doesn't add +6 on top of what you already have. It would be like a mini striker that moves squads of knights instead of rushing ahead alone.