According to the info so far...yes, Murmillo requires 1h Sword instead of Rapier or Spear, unfortunately.
Well, I have some alternative options before you re-roll:
1. Change Weapon
Since most of the skills prior to Rank 8 are far weaker than Rank 8 skills, I think it would be okay if you only use 1h Sword+Shield and only use Murmillo skills. Of course, most of your previous rank skills would be useless, but only attacking skills (which is outdamaged by Murmillo skills) while your buff (if any, except Finestra) can be used without weapon restriction. Well, even if there was, you could use Weapon Swap attribute as well to switch your weapons depending on the need.
2. Advance to Lancer
Since you're into spear build, Lancer would be a viable option...if you have the slot for the pet, that is.
Hoping for the best for you. Because I think re-rolling from Rank 7 must be sucks really hard

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