Do we really need more magic items?
Probably not, but here are two new Spelljammer-specific items I created for my campaign. Take `em or leave `em.
These magical lashes were created by interstellar slavers to subdue rambunctious slaves without risk of killing them. A chainman's whip is used much as a normal whip (requiring an attack role), but the damage caused is temporary, fading afterwards just as damage from an unarmed attack does. The damage is still very painful, however, and character reduced to 0 hp by a chainman's whip is rendered unconscious for 1d10 rounds.
A chainman's whip is actually made of small, black metal links (in other words, a chain), rather than the traditional leather. The whips are relatively common among the Chainmen slavers; nearly all Chainman ship captains possess one.
The helm lock was created by a group of human wizards who didn't like other people using their ship helms. A helm lock is grey metal disk about four inches wide and one-half inch thick. When placed against any flat surface, the helm lock will affix itself to that surface, and change color to match.
The true magic of the helm lock becomes apparent only when attached to a spelljamming helm, where it magically intensifies the connection between user and helm. (The "user" is the first spellcaster to use the helm after the helm lock is affixed. The spellcaster does not need to be the person who placed the lock, or even know it's attached.) While this intensified bond does not improve helm functioning, but prevents the helm from functioning for any subsequent user, so long as the helm lock remains attached. Once removed, the three-way connection between helm, lock and user is nullified, and the helm may be reused on a different helm and/or helmsman.
The helm lock has no special magic preventing its removal from a helm, but its camouflage ability may prevent a character from noticing the lock. (The DM ™ may require a Detect Secret Doors role, Wisdom check, or similar test.) Spells such as wizard lock may be used to more permanently attach the helm lock to a surface.
While providing increased security, the bond created by a helm lock has one unfortunate side-effect: the helmsman is much more susceptible to damage. Any critical hit against a ship using a helm lock automatically causes a Spelljammer Shock! result, in addition to the normal effects of the critical hit. Furthermore, the helmsman is disallowed a saving throw against the spells disable helm, destroy minor helm, or destroy major.
So far, only helm locks for traditional magic-fired helms are known to exist. Even the Arcane do not yet know the secret process used to create helm locks, and will pay no less than 1,000 gpv to acquire one for study.