It seems like three conversations should take place.

A Conversation Between the Group and the DM (Minus Hannah) This conversation should be a reflection on the items that have been dropped, found, or added to the game and the fairness of them. It's possible that in the case of the sword, the DM made a mistake when creating the item or implementing it if the campaign told him to put it in. The darts may have been intended to be used in specific scenarios (Like a player who is chatty outside of the game to the point it majorly disrupts the flow of the game) and the DM simply forgot to tell Hannah and doesn't know how to confront her about it himself.

A Conversation Between the Group and Hannah (Minus the DM) This conversation should be to try and convince Hannah that they don't need silence players in the meta to be heard. It's possible that they're fearful that if they don't have the amount of control they currently have, their character will die. Clarifying that as a group, you won't just idly watch her character die, and assuring her that her opinions about group plans will be heard may help convince her that she doesn't need that much control.

Both these conversations will ensure that your group can have an honest discussion with both Hannah and the DM in an environment that doesn't make them feel like they have to jump to eachother's defense.

A Conversation With the Entire Group With the previous two conversations leading into the group conversation, everyone should be much closer to being on the same page. It may be much easier for the DM to admit that they messed up the sword's stats (Or where it was supposed to appear) if they've already been able to admit as much in the previous conversation. It may also be easier for Hannah to accept that they may lose stats on the sword, or be severely limited on the use of the silencing dart if they know that they're already backed by the entire group. The goal here is to help balance the game in a way that everyone can leave the table happy.

As a Last Resort You will need to be prepared for the possibility that there will be a break in your group and hurt feelings. If either Hannah or the DM refuses to work with the group to balance the game, additional possibilities should be explored. Leaving the group by yourself, or breaking the game off as a group seem like the recommended options.

Another option, and I realize this would need to be handled very carefully, is to play around Hannah. If you get silenced by Hannah's dart, scribble notes out. If her sword is wrecking the combat system, or she's taking an authoritative role, take it as a role play opportunity. Deviate from her plans in the heat of the moment. Just be mindful that you aren't using this to shut her out, but to show her that your group is capable of acting as a group without her micromanaging every detail to make sure everything works out the way she has in mind.

Safe travels, friend! I hope you resolve this situation in a way that leaves everyone happy.

It seems like three conversations should take place.

A Conversation Between the Group and the DM (Minus Hannah)

This conversation should be a reflection on the items that have been dropped, found, or added to the game and the fairness of them. It's possible that in the case of the sword, the DM made a mistake when creating the item or implementing it if the campaign told him to put it in. The darts may have been intended to be used in specific scenarios (Like a player who is chatty outside of the game to the point it majorly disrupts the flow of the game) and the DM simply forgot to tell Hannah and doesn't know how to confront her about it himself.

A Conversation Between the Group and Hannah (Minus the DM)

This conversation should be to try and convince Hannah that they don't need silence players in the meta to be heard. It's possible that they're fearful that if they don't have the amount of control they currently have, their character will die. Clarifying that as a group, you won't just idly watch her character die, and assuring her that her opinions about group plans will be heard may help convince her that she doesn't need that much control.

Both these conversations will ensure that your group can have an honest discussion with both Hannah and the DM in an environment that doesn't make them feel like they have to jump to eachother's defense.

A Conversation With the Entire Group

With the previous two conversations leading into the group conversation, everyone should be much closer to being on the same page. It may be much easier for the DM to admit that they messed up the sword's stats (Or where it was supposed to appear) if they've already been able to admit as much in the previous conversation. It may also be easier for Hannah to accept that they may lose stats on the sword, or be severely limited on the use of the silencing dart if they know that they're already backed by the entire group. The goal here is to help balance the game in a way that everyone can leave the table happy.

As a Last Resort

You will need to be prepared for the possibility that there will be a break in your group and hurt feelings. If either Hannah or the DM refuses to work with the group to balance the game, additional possibilities should be explored. Leaving the group by yourself, or breaking the game off as a group seem like the recommended options.

Another option, and I realize this would need to be handled very carefully, is to play around Hannah. If you get silenced by Hannah's dart, scribble notes out. If her sword is wrecking the combat system, or she's taking an authoritative role, take it as a role play opportunity. Deviate from her plans in the heat of the moment. Just be mindful that you aren't using this to shut her out, but to show her that your group is capable of acting as a group without her micromanaging every detail to make sure everything works out the way she has in mind.

Safe travels, friend! I hope you resolve this situation in a way that leaves everyone happy.