In the manga,
Silphy is a member of the Sweeper Alliance, specializing in body combat. She faces Deek Slasky in battle but is frozen solid by his continuous freezing attack. As the ice spreads through her arm, Sven arrives and fights Deek, weakening him enough that he can no longer maintain the freezing spell, thus saving Silphy.
In the anime version,
the scenario is similar, except Deek does not appear. Instead, Silphy is attacked by Preta. Sven steps in to fight Preta and saves Silphy from the assault.
Source: Wikipedia
