Before Spartacus and the rebels leave to attack the brothel, Crixus tells him that it's not his fight. To which Spartacus replied, "I gave my word; blood and honor. It yet speaks to the man." These are the very same words he shared with Sura in "The Red Serpent" before leaving for war.
The opening battle sequence is the final time that Spartacus is seen fighting with the dual Sica that were purchased along with the Serpeant armor in the Blood & Sand episode, "Delicate Things." From then on, Spartacus is seen fighting with a single Mainz-Fulham gladius.
The Dagger that Spartacus now wields on his shoulder hilt, is depicted with the same prop that was used as the Thracian dagger bought by Numerius in "Blood & Sand." Storywise, whether or not Spartacus reclaimed the same dagger after Numerius death, is never depicted.