CapnZapp
Legend
Let's use this old ASP to create a dozen fully 5e-compatible magic items! 
http://archive.wizards.com/dnd/D2Demo/full_item_generator.asp
Just a fly in the ointment for Wizards
Good thing enemies take 2d4 damage each time they successfully hit you with an attack.
While you are wearing the Fine Robe of Protection, bludgeoning, piercing, and slashing damage that you take is reduced by 3. You also gain +1 bonus to AC, provided you wear no armor.
The first property we'll implement as "while wielding this weapon, you gain advantage on saving throws against being charmed".
Healing yourself 5 points on average for every hit is mega powerful. A balanced version might be "you gain 5 temporary hit points each time you make a successful attack with this weapon".
Ability changes are best kept to even values.
While attuned to this Longsword, your proficiency bonus is increased by 1. Your Rage Damage (your bonus damage while raging) is doubled for attacks made with this weapon.
This this was generated as a fairly high-level item, I thought its interest would mainly lie in its ability to break the twenty barrier.
"user is invisible on any round he or she does not move, attack, or cast a spell"
The second would make sense for a weapons user or something like a wand. What we'll do is this:
The staff has 10 charges. As an action, you can spend 1 or more of its charges to recharge another magic item with charges you are attuned to and are holding, up to its maximum.
Additionally, when you cast a spell that has a casting time of 1 action, you can spend 2 charges from the staff to change the casting time to 1 bonus action for this casting.
The staff regains 1d8 + 2 expended charges daily at dawn. If you expend the last charge, roll a d20. On a 1, the staff becomes a nonmagical quarterstaff.
You need Strength 18+ to attune to this weapon. You become immune to disarm attempts. This pike is shedding bright light in a 30-foot radius and dim
light for an additional 30 feet.
The item is too high level to merely affect other sources of light, so I baked it in. A brandistock is apparently a short spear-like polearm with folding points. Since 5e doesn't support anything fancy I chose the pike based on the damage type: piercing.
We'll begin by making it a +2 Shield. Then it grants every ally (including you) within 30 ft a +1 bonus to AC and saving throws.
While you remain attuned to this shield, all of your ability scores are increased by 4. The scores can exceed 20 but can't exceed 24.
http://archive.wizards.com/dnd/D2Demo/full_item_generator.asp
A throwing axe which never deals less than 5 damage. We'll assume standard 5e statistics. More a curiosity than a truly useful item. At least it counts as magical.
So, a ring that gives one extra spell slot of your highest spell level (up to 5th). Impressive.
Just a fly in the ointment for Wizards
Throwing Axe. 5e doesn't really do numerical bonuses to specific damage types. Let's upgrade this to advantage on saving throws against poison.
It's a Robe providing a permanent Greater Invisibility effect to its wearer. Except it doesn't work on creatures adjacent to you
Good thing enemies take 2d4 damage each time they successfully hit you with an attack.
Another robe. This one grants a powerful version of the Heavy Armor Master feat:
While you are wearing the Fine Robe of Protection, bludgeoning, piercing, and slashing damage that you take is reduced by 3. You also gain +1 bonus to AC, provided you wear no armor.
It's a longsword, but not with any magic bonus.
The first property we'll implement as "while wielding this weapon, you gain advantage on saving throws against being charmed".
Healing yourself 5 points on average for every hit is mega powerful. A balanced version might be "you gain 5 temporary hit points each time you make a successful attack with this weapon".
Attacks made with this dagger score a critical hit on a roll of 17-20. Your Constitution score increases by 2, to a maximum of 20, while wielding this dagger.
Ability changes are best kept to even values.
I don't really understand these AD&D stats, but I'm gonna go ahead with the following:
While attuned to this Longsword, your proficiency bonus is increased by 1. Your Rage Damage (your bonus damage while raging) is doubled for attacks made with this weapon.
When you drink this elixir, your Wisdom increases by 2, to a maximum of 24 for one day.
This this was generated as a fairly high-level item, I thought its interest would mainly lie in its ability to break the twenty barrier.
Staff. The first benefit we can use verbatim.
"user is invisible on any round he or she does not move, attack, or cast a spell"
The second would make sense for a weapons user or something like a wand. What we'll do is this:
The staff has 10 charges. As an action, you can spend 1 or more of its charges to recharge another magic item with charges you are attuned to and are holding, up to its maximum.
Additionally, when you cast a spell that has a casting time of 1 action, you can spend 2 charges from the staff to change the casting time to 1 bonus action for this casting.
The staff regains 1d8 + 2 expended charges daily at dawn. If you expend the last charge, roll a d20. On a 1, the staff becomes a nonmagical quarterstaff.
Oookay, so this becomes a Legendary (+3) Pike that grants a bonus to attack and damage rolls, as well as saving throws. The bonus is determined by the weapon's rarity.
You need Strength 18+ to attune to this weapon. You become immune to disarm attempts. This pike is shedding bright light in a 30-foot radius and dim
light for an additional 30 feet.
The item is too high level to merely affect other sources of light, so I baked it in. A brandistock is apparently a short spear-like polearm with folding points. Since 5e doesn't support anything fancy I chose the pike based on the damage type: piercing.
Yowza! At least it's something appropriate for a level 20 Hell item! What the difference between the two kinds of AC bonus is, I don't know. Let's make it interesting:
We'll begin by making it a +2 Shield. Then it grants every ally (including you) within 30 ft a +1 bonus to AC and saving throws.
While you remain attuned to this shield, all of your ability scores are increased by 4. The scores can exceed 20 but can't exceed 24.
