Relics in 14 are not the same as relics in 11. Just because they have the same name doesn't mean they are the same thing.

They are hardly as good as 11's, take substantially less investment, and in rotation shouldn't always be the best. Giving them a unique WS would make them beyond overpowered due to how the games combo system works.

I assume something like this will happen:

L50 Relics are best ->
Level Cap Raised ->
New endgame content has weapons better than relic ->
new relic quest add on -> Relics are best again ->
new content comes out with weapons stronger than relics ->
level cap ->
new weapons from content better than the previous strongest ->
-> new relic quest add on -> Relics are best again

etc etc etc etc unless Legend's are planned and are similar investment to XI Relics but preferably not a 100% gil investment.