How to Reobtain Year 1 Weapons

Solution 1:

Some legendarys were tied to events like the queens ransom or original iron banner and are unobtainable. Before 2.0 and the Taken King you used to be able to get legendary engrams from lower level strikes (not during the strike itself but in the end mission screen) and those would decrypt into older legendarys. Though those older strikes were done away with and replaced with the single legacy playlist in the 2.0 update.

So no, aside from gear in the older Raids and Prison of Elders since that is tied to still existing activities, you won't be able to reobtain year one equipment.