Just wanted to give an update. Currently on Tip.It, the Armadyl/Bandos/Ancient Vestments are listed as a possible reward from level 2 clues. However, in the Costume Room of the P.O.H. it lists those Vestments as level 4 rewards. I took a screen shot of my Treasure box. At the top it says 'Elite-Level Treasure Trail rewards'

 

 

This is because the final two components of those sets come from elite clues. If you look, the old sets are the same way, just moved down a clue level.

As GaVaTi said, Sets are stored in the costume room based on the highest level of clue required to get any of the components, and this only really effects the vestments which are spread across 3 tiers of clue rewards (top and bottom, cloak and mitre, crozier and stole).