Variant for charged magic items "magic focusing"

Wanting to take a break from the races of Eska (even though I only have the warforged left), I've been reading through old issues of Dragon Magazine for things to convert to 5e. While I've found plenty of cool articles and short fiction to read, (not to mention Snarf Quest and Wormy), there has been a lack of things that would port well into 5th Edition.

Then I was reading issue #111. While I've barely got into the issue, the first article really caught my eye. Good Stuff, For a Spell. Magic focusing, a new dimension for possessions, by John M. Maxstadt. It provides a variant idea for powering charged magic items such as wands and staffs.

The old school 81 charge wand of fireballs, for example, never struck my fancy. Players either hoarded charges and mostly forgot about them, or used them at every opportunity, blasting everything until all charges were gone.

I'm not really a fan of 5th Edition's 7 charges that regenerate, either. I'm not really sure why, but it just doesn't seem right to me.

What the article presents is really just an idea, not fully fleshed out. He leaves "the details of the individual items up to the individual DMs and designers." He calls them "magic focusing items".

What a magic focusing item does is allow a spell caster to power the item with their own spell slots to cast the spell. Using the wand of fireballs that I referenced above, if using the magic focusing variant the wand itself has no charges, but allows you to cast fireball if you power it with at least a 3rd level spell slot. You don't have to have fireball memorized, or even have it as a spell known to cast it, as long as you focus your spell slot through the wand. Powering the wand with a 5th level spell slot works the same as casting a fireball with a 5th level slot.

Magic focusing items can't "store up" spell slots cast before hand. The spell slot must be used at the time the effect is desired.

More than wands can be magic focusing. Any item with charges can be "converted" into a magic focusing item. A staff of fire can cast burning hands, fireball, or wall of fire, as long as the user powers it with the appropriate spell slot.

Many other items can me magic focusing as well. A ring of feather fall, an amulet with the shield spell, a bracer of web.

Non Spellcaster Variants
This also has me thinking about other ways to power the magic items other than spell slots. Using spell slots makes the spell focusing ring of feather fall useless for a non spellcasting fighter.

An idea I've been toying around with for Eska is using a sacrifice to power magic. This can be either sacrificing yourself or another. I haven't worked up the details of this, yet, but a full system is coming.

The basic quick and dirty would be using hit dice and levels of exhaustion to power magic. Each hit die or level of exhaustion expended is equal to a spell level.

Eska
On Eska, the gray elves guard the art of wizardry closely. Very few non gray elves are ever taught. For the other races, magic comes naturally in the form of sorcerers or by making pacts as warlocks. I'm using the spell point variant rules for sorcerers in my game, and just rolling sorcery points into the spell point total, and making them interchangeable. This makes the sorcerers extremely flexible with their limited spells known.

The gray elf wizards, wishing for some of this flexibility, developed the [I]magic focusing[/I] items.