WMG / RosenkreuzStilette

Warning: Possible spoilers ahead.

Rosenkreuz's true power runs on The Power of Friendship
Just as his reincarnation Spiritia shows us, she has full trust towards her close companions and vice versa, and that's what gives her their powers. It was also said that Rosenkreuz once had 8 close friends, making this a case of Generation Xerox.

Though it may be obvious when you think about it, this WMG does fuel the one below...

If Iris ever get her hands on the "Blade of Rosenkreuz", she'll end up unable to use it
Because she lacked the friendship capacity that Tia has. Worse, it may even backfired spectacularly (This Troper reminisces how, in Devil May Cry 3, Arkham got all the ingredients to harness the power of the Dark Knight Sparda, but ended up turning into a blob, and his lack of compassion that Sparda had is the reason why that happens).

The Blade of Rosenkreuz is a real weapon
Just like Grollscwhert or Weissilber, it is a sword that, going by its theme, store and harness the power of his close friends. When he sacrificed himself for the Empire, they're buried separately - it may explain how there are 2 walking reincarnations of him, with separate abilities.

Predictions if there is a sequel to Freudenstachel
IF, because this game seemed to have ended on a high note, but if there's one...

Iris wasn't killed, but put in ice by Freudia. Unfortunately, some poor schmuck would end up thawing the ice that sealed Iris. At this point, Iris stops being an Expy of Dr. Wily and evolves into an Expy of Dr. Weil, an even higher order of Complete Monster and this time, after having a normal Magus (Freudia) beat her, Iris completely lost it. She no longer wants 'fun', but wants bloody vengeance to the RKS. But around this time, Iris' true nature has been revealed to public and she was considered a menace and a monster. Iris then decides, "If people will not recognize me as their God, then I will become their Devil!!" So, using everything she got in her disposal, not giving quarters or chances for 'amusement', Iris turns the world into a living hell and at this point, either Spiritia, Freudia or anyone else in RKS have got to stop her at all cost, and this time even killing and destroying her own life force ends up being an option. But what would they have to sacrifice, and will it be inevitable or avoidable?