Valkyries ("choosers of the slain") are beings from Norse mythology in servitude of the god Odin; their task is to choose who may live and who may die on the battlefield. Among those who have fallen, they select heroes to transport to Valhalla, the afterlife hall, so that these chosen ones will fight on Odin's side during Ragnarök. Valkyries are depicted as female battlemaidens on horsebacks.
I actually struggled to come up with a name for this shrine, but settled on this so as to avoid "If You Still Believe" due to its length and to stop myself from coming up with names as cheesy and obscure as "Hier" (French for "yesterday", German for "here", thus combining The Legend of Dragoon's blurring of past and present).
Rose may not exactly do the choosing, but she certainly is the one who rules over the life and death of each Moon Child that is born, who she kills as part of a mission that goes beyond a single person's life. Valkyries are heavily associated with battles and war, which ought to reflect Rose's reality where, although the Dragon Campaign is over, the war and battle still go on.
There's also this passage on Wikipedia (do not cite Wikipedia for actual research, folks) that just... struck me due to what I associate The Legend of Dragoon with:
Simek says that the valkyries were closely associated with Odin, and that this connection existed in an earlier role as "demons of death". Simek states that due to the shift of concept, the valkyries became popular figures in heroic poetry, and during this transition were stripped of their "demonic characteristics and became more human, and therefore become capable of falling in love with mortals [...]."
Myths and legends are a constant element in the game, and the Black Monster is featured in so many of them. These tales can change as time passes, as does the player's perception of the Black Monster – and ultimately Rose – as they uncover more and more of the true story. In the end, it turns out that the people's perception of Rose is very warped – understandably so, as Rose's killing is very real, but that twisted grasp on the Black Monster completely misses the motives behind those actions (as it was intended to be, I suppose), thus leading to Rose being cursed and severely misunderstood.