Without knowing the injuryies, the type of weapon used (if any) then one can only tell you that he could receive anything from probation to several years in jail.
Every case varies depending on the law and the facts. Because questions often fail to disclose important facts, these 'answers' cannot and should not be relied upon as a replacement for a full or complete review of an actual case by a retained attorney. It is axiomatic that one only 'gets what they pay for', and this is one of those situations where such a phrase generally applies.
Your brother should be discussing his case with his lawyer. If he doesn't have a private attorney, he should have been assigned a public defender. You are not really doing him any service by discussing his case in a public forum. This is not a confidential website.
If he's going to plead guilty, he should know in advance what he's being sentenced to. Speak to his lawyer. Generally, he'd be looking at probation or up to 5 years pen time. www.galivanlaw.net