PVP would be more fun if we can add more peoples inside the game.. Something like Counter strike... everybody start with zero modding weapon n frame.
To make it link with PVE farming material, players will only able to equip mods and weapons that they already have within they account. By using DOTA concept, maybe put some "arsenal station" within respawning area for peoples to buy MODs n Weapons that they have in order to make it more powerful. Still limited to what mods and weapons they have inside the own inventory. At the same time will drive people to play PVE too in order to get more variety of mod and weapon. Only need to introduce new type or resources that need to farm within that PVP game so player can farm it and enhanced their frame and weapon to the level that they wanted.
Example, killing player will rewards "in game endo", player who able to kill more player able to leveling their mod based on how much endo they get.. more high level mod they have = more powerful frame or weapon...
Just a cent of idea..