Was Callandor constructed during the War of Power?
Yes.
Was it used in the War of Power?
Yes, that is how the flaw was discovered.
Why didn’t they ward/buffer Callandor ?
The flaw with Callandor is simply a manufacturing flaw. He went on to talk about how they were at the end of their tech age with only a few sho-wings and jo-cars left. A couple of shocklances were still around but they were not as prevalent as they had been. Anyway they had been mass producing ter’angreal , angreal , and sa’angreal , and there are bound to be flaws with the products. The flaw with Callandor is simply one such flaw.
This is specifically referring to the lack of a buffer.
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