Downscaling agony infusions.
You can’t.
You can only trade the +16 for the new +stats AR infusions. 14’s and 15’s are in an awkward place where you either need to upgrade them to 16’s, or sell them.
The reasoning is the havoc it would cause to the infusions market:
https://forum-en.gw2archive.eu/forum/game/dungeons/Update-on-16-Infusions/6284558
- If you want Stat+5/AR+9 infusions, upgrade to AR+16.
- If you don’t want those, sell the AR+14, AR+15 on the TP.
- If you want the least effort, sell and buy the stuff you do want. (The ‘cheapest’ option is often only slightly better than the others.)
FYI
This is also being discussed at:
https://www.reddit.com/r/Guildwars2/comments/5ksob4/15_agony_resist_can_i_downscale_this_to_2_14/
Highlights of that discussion include the fact that are currently around 230k AR+1 on the market. Offering deconstruction of AR+14 & AR+15 would add around 360k AR+1 (or the equivalent). A sudden doubling of AR (and then some) would would drop prices like a stone — and that just accounts for the 14s & 15s already on the market, not the ones that are in the hands of folks such as the OP, who don’t know what to do with them.
Thanks for the replies I managed to pickup a second +15 and got started on a condi set with the +5 condi +9 agony resist infusions. Thanks again for the very informative replies it is much appreciated!