[RPG] How does War Caster interact with Hexblade

You're right, you're kind of stuck.

Thankfully, the action economy of 5e works in your favor here.

Here's what you need to do:

• Select a crystal as your Arcane focus
• Wear the crystal on your body (necklace, pendant, whatever). Components pouch also works here as there is no action economy on drawing stowing one of those.
• When you want to cast a spell, drop your weapon and touch your crystal
• When you're done casting, pick up your weapon.

This takes no additional actions, is perfectly legal (nothing specifies how big a crystal must be, just that you have a hand free to use it. (dropping a weapon costs you nothing, picking it up is your interact with object that's free with an attack or move).

The only real risk here is that if you do this a great deal, an enemy might begin to ready actions to attack you, or even move away from you while your weapon is stowed. This is something you'll have to live with for this to actually work.

Last thing that I'll say is that you should talk to your Adv League GM, or even seek out an answer from their twitter feed on this. GMs for Adv League are supposed to be lenient and use common sense in their rulings as the ruleset is flexible by design.

No, the War Caster feat does not allow you interact with a spellcasting focus with a full hand, only complete the somatic component of a spell with one. The second bullet of the feat makes the character skilled enough to complete the somatic component of a spell in the heat of combat without having to stow a weapon or shield first.

Page 203 of the 5E PHB, under Material (Components) reads:

A spellcaster must have a hand free to access a spell's material components - or to hold a spellcasting focus - but it can be the same hand that he or she uses to perform somatic components.

War Caster does not free your hand; it allows you to complete the somatic component of a spell while anything is in it, not just your focus. You must somehow interact with your focus (or the material components) to complete the material component of a spell that requires one, regardless of which hand does the somatics.