A thought about the eye and sealing the DO

[Orderofolde]

While they had access to Wells, no one had a need to store a concentrated form of the power during that time when everyone was relatively strong and in the case of LTT and the Hundred companions, arrogant.  Your logic is correct, however.  If an Eye or a pool had existed and was used, then it would be tainted and would have driven them mad.  The world would have broken but the source wouldn't be tainted.  

 

The only use for a concentrated well like the Eye was cleaning and storing the source in a physical form which concentrated it, whether that was the use or an unintended consequence we don't know.  We do know that the Aes Sedai hid the banner and a seal and the HOV beneath the pool, likely based off prophecy.  And we also know there were the same number of Eyes in RJ's original manuscript as there were seals, iirc.  That was reworked and for a time it looked like for each Forsaken Rand and CO killed that a seal was broken, but then that fettered out.  I attribute all that to early bookisms, the editing process where the publisher had a lot more input early on and so forth.