Riven's sword

Wherever we see the phrase "Rune" in world of league of legends , it seems like we are dealing with some sort of unstable magical power. judging by her recent story this sword , a Runic blade, seem to be having a hold on Riven (or had in this case) , blinding her to certain things before her eyes.can't exactly call it, controlling. that's why she felt so lost and didn't remember much of that happened before those events.

Right now that hold on Riven is broken, but the sword still has its power. there is not much evidence to support any claims about the sword. but to me it seems like since the sword is broken its no longer as powerful as it was, hence why it can no longer "control" Riven, even when it was made whole again in that trial. the power of the sword is faint enough to give Riven her memories back.

The nature of this sword is truly disturbing and raises a lot of questions about Noxus and its commanding officers. is this a common thing? do they control their generals and soldiers regardless of their loyalty and allegiance? is Riven a special case and they had doubts about her? too many unknowns!