Massacre does he need sigs to be good

Moogie

just got him as a 6* not gem etc but i know hes decent is he worth it

Zuro

Not really although it makes his ramp up faster

Fantomaxop

Low sig Massacre primary ramp up strategy is to hit block until he enters "Ignited" mode.
Alternatively you can just hit opponent and try to build up charges with critical hits. Sig helps with that a lot.