Not sure if working as intended or if this is reported. At first the you had to do 100 missions (crusable, strikes, gambit or the vex thing) to get the catalyst. Then they changed it to 400 but maked it so that if you use it in these events it goes up by 4 or just do it it goes up by 1. Now you only make progress if you wield the weapon in an event and progress gained is one. If you do not wield it you get no progress.. So you just made 4 times more difficult to get... I sincerely hope this is a bug... I got the this seasons weapon catalyst unlocked and masterworked waaaaaay faster than the vow... It also may be possible that the mission is not working properly for me. Didn't really follow the progress before this season.