So I’ve never done homebrew stuff before, but i have two magic item ideas that I would really like to make…

• One its a type of weapon (inspired by kill bill volume one) that functions as a quarter staff that can be turned into two short swords (of sorts), not through magic, but because of its design.  
  The quarterstaff can be separated by half lengthwise, revealing two blades hidden inside of each of the halves. Each of the blades it’s attached to half of the quarterstaff, making it a sword with quite the long grip/hilt. 
  The hilt of one sword functions as the scabbard of the other, and the staff can be reassembled by holstering the blades. 
  I want for this type of weapon to have magical variations, including a legendary one with a few spells and bonuses to both ac and attack roles. 
  
  
• The second is a sentient magical item of sorts, its a fey “familiar-like” bird shaped being that turns into a short sword. Once attuned, the bird creature will bond with its master like a familiar does, but unlike a familiar found by the “find familiar” spell, the creature will be able to attack in the player’s behalf, in its bird form as well as its sword form. 
  The creature  can roll perception checks in its sword form, and communicate its findings telepathically to whom ever holds the sword. 
   then, when the sword is thrown into the air, the sword will transform into a bird creature of the same mass as the weapon, the blade turning into a beak and the the quillons(cross guard) into  wings . 
  
  

 Again i have never done this before so im really looking for a place to start, any advice on the implementation, or the design of this item ideas is VERY much appreciated. 

thanks!
—charly

All that looks complicated. Let me see if I can provide some insight.

• A quarterstaff that turns into 1 or 2 shortswords:
  • For the mundane variety, all you really need to do is give them a quarterstaff and 1 or 2 shortswords.
    • I'd adjust the weight on the quarterstaff to account for metal blades being inside the stick. Then make the swords have 0 weight. 
    • Add notes to each of the weapons explaining the mechanic of pulling the quarterstaff apart to have 2 shortswords. 
    • You might check the Dual Wield box on one of the 2 shortswords since the player could use their bonus action to trigger two-weapon fighting since the shortsword is a light weapon.
  • The magic item variety, you would need to homebrew a quarterstaff giving the buffs and spells you want. You would also want to homebrew the shortsword simply for the purpose of making it a magical weapon. Since the quarterstaff would have the spells and buffs built into it, the shortsword wouldn't need them.
• For the familiar sword, you just need to make a magic weapon with all that flavor text added in. Tell the player to add the familiar type they want to the Extras tab and to ignore the text blurb saying a familiar can't attack. But you might want to rethink what you're giving them. Giving a familiar it's own attack is pretty powerful. Even Pact of the Chain warlocks give up an Action, or if they take the right invocation their bonus action, to have their familiar attack. Whereas your description does not mention anything like that.

I agree with Mairondil about the quarterstaff, however for the familiar sword, I'd suggest starting with a Dancing Sword and adding flavour text to it that it can transform into a CR 0 bird or back again as part of the bonus action used to command it.

For item 1, I would argue that renaming the quarterstaff and adding the special weapon property is sufficient for the mundane version due to it already being versatile with 1d6 like a shortsword.

For item 2, and as a familiar maniac myself, I actually have an item published that behaves somewhat similarly that you could use as inspiration if nothing else.