Lots of you didn't like the new combat system in 1.9. Let's fix that and dump in more cool features!

+ New /gamerule, attackDelayMultiplier. Set to 5 by default, can be changed to 0 for pre-1.9 behavior.
+ New damage system with different types of damage, Crushing, Slashing, and Piercing. Different mobs are vulnerable to different types of damage (i.e. Skeletons take extra damage from crushing, most animals take extra damage from slashing, fish take extra damage from piercing). The type of damage an tool or weapon deals is listed in the tooltip.
+ Crafting recipe for Unstable TNT (the kind that ignites when punched). Craft with 2 flint and 1 TNT to get 1 Unstable TNT.
+ Function for the Fletching Table. You can make special arrows with it, up to a full stack at a time.
+ New arrow, Antigravity Arrow. Crafted in a Fletching Table with an Eye of Ender. Flies in a straight line!
+ New arrow, Flaming Arrow. Crafted in a Fletching Table with a fire charge. Acts like the Flame enchantment.
+ New arrow, Explosive Arrow. Crafted in a Fletching Table with TNT. Explodes on impact with entities, but not with the ground. Does not destroy blocks.
+ New arrow, Highly Explosive Arrow. Crafted in a Fletching Table with Unstable TNT. Explodes on impact against anything and everything. DOES destroy blocks.
+ New potion for the Blindness effect. Brewed with an ink sac.
+ New weapon set, Shortsword. Short reach, mediocre damage, swings pretty fast.
+ New weapon set, Broadswords. Decent reach, great damage, swings slightly slow.
+ New weapon set, Longswords. Great reach, decent damage, swings kinda fast.
+ New weapon set, Greatswords. Great reach, great damage, swings quite slow.
+ New weapon set, Spears. Crafted like a shovel, but diagonal. Reaches pretty far, and can be thrown like a trident! Only trident enchantments that work are Piercing and Loyalty.
+ New weapon set, Glaives. Upgrade Spears to these. Reaches even farther, but cannot be thrown. XP will be returned to you for dispelling the Loyalty enchantment, but Piercing will stay.
+ New tool/weapon set, Hammers. Crafted like a pickaxe, but with blocks and logs instead of items and sticks. Breaks glass and stone blocks faster, but not as fast as a pickaxe.
+ New weapon set, Sledgehammers. Deals more damage than Hammers and reaches just a little bit further. You also get a slowness effect while holding one, it will compound with armor slowness.
+ New armor sets, Heavy Armor. Provides more protection, but slows you down by 50%. Chain and leather do not have heavy variants.
+ New armor sets, Medium Armor. It's just the default armor, but now it slows you down by 25%. Leather does not have a medium variant, it's just... leather.
+ New armor sets, Light Armor. Provides less protection, but lets you move at full speed.
+ New shields for all equipment sets. Differences are what you would expect, diamond lasts longer and provides more protection than wood.
+ New recipes for the Smithing Table. Upgrade weapons and armor with it! Add materials of the corresponding set (leather, iron nugget, iron ingot, gold ingot, diamond) to upgrade a tool/weapon/armor piece to the next level, the exceptions being Hammer-->Sledgehammer, which takes blocks and Spear-->Glaive, which you use sticks instead. You have a choice of upgrading a Sword to a Longsword or Broadsword, but both can be upgraded to a Greatsword.
+ Give an armor stand a hay bale as a hat to turn it into a training dummy (it never breaks when punched)! Right click it to remove the hay bale and turn it back into an armor stand.
+ New weapon, the Starblaster. Crafted with two nether stars, a beacon, a lever, and five obsidian, right click while aiming at a mob to deal immense damage with a particle beam. Also mines blocks! Has a lot of durability, but it will get too hot and burn you if you use it for too long. You'll need to wait for it to cool down or throw it in water to be able to use it again.
+ New accessory slots for equipment! This will come in handy.
+ Crafting recipes for chain armor with chain blocks.
~ You can now click and hold to attack. No more tired fingers from spam clicking, and no more tired brains from trying to concentrate too hard on timing!
~ Elytra are now equipped in an accessory slot. You can wear them with chestplates now!
~ Wear and access a shulker box by putting it in the accessory slot. It's like a backpack, and you don't even have to place it to take items out!
~ Witches and all other illagers are now "neutral" mobs, not hostile (like wolves/zombie pigmen)! They can be traded with like villagers, but they attack you if you attack them. Obviously, you cannot trade with them when they are trying to kill you. The exception is during a raid, in which they are immediately hostile. Witches trade potions, ingredients, and various other alchemical equipment, Pillagers trade crossbows, arrows, and crossbow-related enchanted books, Vindicators trade axes of all materials as well as Sharpness, Knockback, and Efficiency books, Evokers trade spellbooks and enchanted books of all kinds, and Illusioners trade their spellbook, bows, arrows, blindness potions, and nasty tipped arrows.
~ End Crystals make a soft humming sound.
~ Putting/holding certain items in your hands makes a sound (e.g. swords make a "shwing!" noise, Blaze rods, torches, and fire charges softly crackle, End Crystals make that humming sound as described above in your hand, too!).
~ Sword crafting recipes make shortswords now.
~ Armor crafting recipes make light armor now.
~ Bows and crossbows can be repaired at a fletching table with string.
~ Tipped Arrows no longer require lingering potions, use any type (normal, splash, or lingering).
~ Tipped Arrows are made in the Fletching Table now.
~ Spectral Arrows are make in the Fletching Table now.
~ End Crystals now render what the actual entity would look like when you're holding it. In first person view, it will bob up and down in your hand. In third person however it will not bob, but float above your hand instead. An odd perception difference, adding to the mysterious nature of the End Crystal.
~ Old armor will be replaced with light armor as soon as you load your world.
~ Old swords will be replaced with broadswords as soon as you load your world.
- Removed Flame enchantment because of new flaming arrow items.
- Removed Herobrine.