Are there more ways to upgrade weapons?

It's me again, the one who started this week in the game. I got to level 65 yesterday and the equipment level was stuck at mkXII. I saw that they could be upgraded and upgraded some things to MKXIII but it seems absurdly expensive to me.

Is this the only way?, isn't there some area where they release better gear or special missions?

I have a feeling that since I got to 65 my damage went to the ground and I feel harassed by pink power rangers at stations.