I agree the TEC ships are undergunned.
I've been looking at the spec files, and for a trading race, there isnt that much difference between all of them. TEC should have a definite trading advantage and they dont.
The argument for being able to build more ships doesnt wash. At some point you will reach the fleet cap, and if you are in a large game, protecting more than one planet with sizable fleets, an enemy who isnt doing that can hit you with everything they have and there is no ability to outnumber them. Now, if the TEC got 25% more capital ships and fleet size, then maybe that argument would hold. But they dont, since all are the same.
Protecting block points requires some planning. You need to figure out where a battle will be faught, and have multiple repair towers in place, and ensure your fleet stays in the protection area. Dont use Gauss popguns, use the points to put in more hangers and repair towers. Then garrison the planet with light carriers so you have about 30 squadrons or more. Put in Heavy Cruisers for interception and flak frigates to take out enemy fighters.
You need to upgrade your capital ships as the battle goes on. And its essential to do all the ship research as fast as you can to give yourself every improvement you can get.
Most of that doesnt help when your attacking though.
If a planet has a Nano Weapon Jammer, you take that out FIRST. Throw everything you have at it and take losses to kill it asap if you have to. Until you do, your toast as your weapons are basically neutralised. If you know in advance the planet has one, then plan your exit vector to bring you to in at a place with an open line to it. Use a suicide recon if you need to find out where it is.
Likewise the Advent Antimatter recharger. That device will continually recharge the capital ships so they can use their special weapons against you more often. That is also a huge advantage.
Tactics on the battlefield are everything, as is having all the right ships in the right quantities with you in the right place.
The TEC is by its nature at a disadvantage, and I'm modding to correct that.
But you also have to maximise its strengths, and have strategy in place to allow you to survive. It also helps if you choose senarios that allow you to defend better, such as less and shorter phase lines. Less attack vectors at you, distinct choke points to hide behind.