The phrase "hast a swing at" implies an action of attempting to hit or strike at something, often in a forceful manner. While its antonyms may differ based on context, some possible options include "restrain," "refrain," "withdraw," "shy away," "avoid," "evade," "forgo," "abstain," and "hold back." Each of these terms suggests an act of holding back or refraining from taking action, rather than engaging in it. For example, if someone advises you to "restrain yourself" in a confrontational situation, it means to exercise self-control and avoid lashing out physically or verbally.