That's the benefit of majority verdicts.Before them, and in the US still, one person could refuse to convict and there'd be a retrial. If it happened again in the retrial, the jury would be discharged and the accused would walk free, formally acquitted, since, by convention,the prosecution would offer no evidence.
If the dissenting juror thought the accused was the assailant, they must have misunderstood the judge's direction on murder. It is sufficient that the accused intended to cause grievous, that is really serious, bodily harm; it is not necessary to prove an intent to kill; and the multiple injuries from a weapon surely demonstrate that lesser intent.It could only be manslaughter if neither intent was proved.