Modifiable Maces - Charges

I can't help but notice that the item model for the mace has a slot, so that got me thinking. What if we can put something inside? 

Charging Up

The idea is that you can put certain materials into the mace which will add a limited effect. Whenever the mace does a heavy attack (the attack that knocks back entities) it will also utilize a charge to also do an added effect. For starters, most effects will have 4 charges. The material can be applied either right-clicking the mace with item or vice-versa or perhaps it could be done by having the material in off-hand and mace in main-hand and then right-clicking.

Ideas for charges can be Blaze Powder causing nearby enemies to be set on fire. Snowball-charges can apply slowness. Or Breeze Charges to increase knockback. The idea is to add more unique variety and utility for the mace without the use of enchantments.

Other Fun Ideas

Chicken Egg - Spawns 1-4 baby chickens
Slimeball - Allows player to bounce back up 70% of last height
Gunpowder - Causes block-breaking explosions depending on fall/damage
Firework Charge - Creates the firework explosion upon use
Lingering Potion - Places the lingering effect upon attack
Amethyst Shard - Creates a beautiful sound depending on mob or block being hit on
Fire Charge - Sets nearby blocks on fire
Bonemeal - Applies bonemeal to any applicable block in the radius
Torches - Places a torch while also setting the target on fire
Copper Rod - Spawns a lightning bolt in the area
Chorus Fruit - Randomly teleports player