New weapons and armor become available as you progress through the storyline.
In order to always have the best outfit available to you, you need to: 1. Study the key technologies first (such technologies are specifically highlighted in golden color in the "Research Terminal"), they will open access to technologies that allow producing new weapons and armor. 2. Learn the technology needed directly for the production of new weapons and armor. 3. Produce new weapons and armor in the Workshop.
Some weapons and armor can only be accessed through special offers. Such items are added to your inventory immediately after the purchase - they do not require the study of technology and they do not need to be produced.