I mean, based on the Patreon link someone posted, if you need a by-the-book explanation it boils down to
1) Roy's sword was magical or non-magical
2) Xykon silently cast Superb Shatter or some other enhanced form, then just said "Shatter" for dramatic effect.
3) Roy's sword then broke, because Xykon dropped a big heavy-duty version of the spell to make sure the Disrupt effect couldn't be used.