Upgrade to the next signature ability node and get less health upon resurrection than the previous one? For reference here's Filia's signature ability path. The next upgrade is supposed to be better than the last. Based on the Big Top Cerebella opponents I've fought. It looks like the 25% health after resurrection isn't just a description mistake, it actually reduces it to 25% from the previous 50%. I think it was meant to be 10%, then 25%, and then 50% at the final node path but instead the 25% and 50% orders got mixed up.