The post where someone is talking about a "recast timer" on it looks to be running his mouth off a bit. He also claims that the Divine Aura song lasts 30 seconds with a 30 minute recast. I'm not sure how reliable his info can be taken.
According to the second link you provided and these two pages..
http://brisk555666.tripod.com/id7.html
http://twilight.uh-oh.jp/eq/tips/b_song.html (use Google translate)
.. Denon's Bereavement was listed in the spell file as an AE DD/Stun(0.0 sec). However, according to a comment in your second link dated 9/30/2000, it operated as a DoT anyways.
I can't find any confirmation saying this song had a recast timer; in fact, my second link above accurately lists recast times for both Kazumi's Note of Preservation and Brusco's Bombastic Bellow, but says nothing about a recast timer on Denon's Bereavement.