Hey there. The individual triumphs are for playing the missions as part of the weekly rotation of campaign missions, on Advanced, Expert or Master difficulty. Despite the 'any difficulty' wording, playing on Normal/Classic or on Legendary through the campaign mission picker does not count for this, it must be the weekly variant. I am not sure why it didn't offer you an exotic choice, but there is another way to unlock it. If you max out Rahool's reputation once, then another page will be added to his focusing options, this additional page, novel decryption, allows you to focus an exotic you've never owned before. Osmiomancy Gloves are not locked to the campaign, originally you had to choose between those and Secant Filaments, the other had to be earned from Lost Sectors. As of The Final Shape though, the unlocks have been moved to Rahool.