Force-fighting with Cleaver makes it attack in an arc to the space you are hitting and the two adjacent spaces regardless of what’s in that space, allowing you to hit two monsters at the ends of the arc even if there is nothing between them.

Applying Cleaver makes it not attack in an arc, for the rare occasions you know you don’t want to attack in an arc.

Cleaver can be invoked to toggle its arc-attacking on and off. This should perhaps not set its invoke timeout, since it isn’t giving the player any particular benefit. However, it’s a bit problematic what the default setting should be; if it starts out in no-arc mode it will be hard for players to discover that it has an arc mode at all; if it starts out in arc mode players may hit a peaceful target in their first few attacks before remembering they need to manually toggle it.

Alternatively, just prompt the player for confirmation if the attack they are about to make is obviously going to hit any peaceful or tame monsters.

Extend Cleaver’s wide-arc hitting behavior to all battle-axes.

A Barbarian rage mechanic (possibly an effect on Cleaver replacing its current damage bonus) where a damage bonus is assessed based on how long ago you last killed a monster. Originally a buff to Vorpal Blade where it beheads anything it hits if the last behead was N turns ago, but this is unbalanced.