I'm reminded of the Scorpion talisman from Storm Front.  If you could use enchanted item slots to create various talismans you could carry on your person (a charm bracelet perhaps?)  Then you just trigger the talisman to conjure the object.  If you are looking for a Sponsored solution there is always Soulfire. 

How is 5e overall, by the way? It sounds like a bit of a mess from where I'm standing, but I don't want to pass judgement on a game I know so little about.

Bit of a mess is a bit of an understatement IMHO.  The minor mess is some of the questionable rule changes made which I can totally live with.  That's just the way it is.  But the standard of editing and writing in 5th edition for the core rule book and the supplements released so far have been nothing short of horrible, again IMHO. 

Doesn't that kind of encompass every kind of physical attack?

So did the toughness only apply to magic, then?

The other way around.  The catch was that toughness only applied to slash, pierce and crush.  So no protection from magic, fire, acid, etc.

I would agree that a threshold invite is only good for that visit.  I am pretty sure that Murphy has tested Harry on more than one occasion using her threshold. 

That's not true. Did the Alphas have to pay a price for their power?

No, they just had to learn how to use their magical potential.

If you want to have a human direct her magical potential towards being strong and fast and tough, you can. Just take an appropriate high concept and whatever Powers seem reasonable.

I've made characters like this before, though I'd have trouble finding one with an actual backstory. Most of the characters I've made are generic.

I'd have to disagree with this.  There is always a price.  Though I do agree with the thought that the price is probably on a par with the power gained.  Part of the problem with making this statement one way or the other though is that we really don't have a complete picture of the Alphas.  They are important secondary characters, sure, but still secondary characters. 

My guess is that their "price" is a little of their humanity.  Not nearly so much as a hexen wulf, of course, since there is no demonic element.  But look at Billy in the last few books.  Definite signs of animal aggression and ferocity.  Not really a typical human response but not surprising from a person that has spent years learning to BE an animal. 

IIRC, the nightmare-demon is actually quite clearly explained as having had to work around thresholds, waiting until Harry's psyche had traversed the veil into the Nevernever, essentially the same as jumping him in the street outside his house.

True but Harry was certain that the heart exploding spell was going to kill him once Shadowman got some of his hair and there was nothing he could do to stop it. 

I suppose if you had 2 objects that could generate noise or vibrations they could be magically sync'd so that if you made one make a noise it would be replicated to the other.  Maybe even just Morris Code.  There is also examples of enchanting crystal radios being used for similar purposes. 

Not very portable but it would be cool to enchant a pair of manual typewriters to send written messages between them. 

The only quibble I have is that a Knight of God would not under any circumstances hurt an innocent.  I have trouble reconciling a wielder of a Sword of the Cross with anyone with a feeding dependency except in some very narrow, limited circumstances.