The Echo was initially an umbrella term for a number of different powers (resistance to tempering was baseline; the WoL was able to see in the past, Minfillia could see the future, some would grow stronger the more they fought, etc.) but the failure of 1.0 and rush to the End of an Era content prevented them from fully fleshing it out. With ARR they dropped the idea that each echo-powered individual had their own unique ability… mostly. Minfilia could still see the future, in early storylines the writers played with the idea that Ascian body swapping was related to the echo, and Iceheart's ability to both manifest and control Shiva was definitely the Echo. Eventually, they went back on all of it again in 3.1. Krile mentions that the Echo manifests in everyone differently, while explaining her own powers granted by the Echo, and SQEX has stuck with this angle since.
For us players, a lot of this back and forth wasn’t apparent as we didn’t have a clear idea what The Echo was, but behind the scenes they were trying to nail it down even into Heavensward, and this is largely why it is so inconsistent and confusing.