Is it possible to use a weapon as a normal weapon and an arcane focus at the same time?

I am relatively new to D&D, and am currently creating my very first PC, a Tiefling Sorcerer with a Draconic Origin. As I was working on my weapons and items, I got into what an arcane focus is and how they work.

Since I read online that a quarterstaff can double as a weapon and an arcane focus, I was wondering if it was possible to use them as both of those things at the same time?

Let me give an example: I am a 3rd level Sorcerer and know the metamagic Quickened Spell and the Shocking Grasp cantrip. I am in the middle of combat, and on my turn decide to attack an enemy within range with my quarterstaff. Before I attack, I decide to expend my two sorcery points to change the casting time of Shocking Grasp cantrip to one bonus action. I then attack and hit the monster.

Can I simultaneously hit the monster, costing 1 action, and cast my Shocking Grasp cantrip, costing 1 bonus action, to deal more damage with my attack?

Casting a spell with somatic and material components with a Heavy-crossbow that is a focus

As stated in the title, I’ve read about casting spells with somatic component with two-handed weapons here.
The thing is that the Xanathar’s warlock invocation [Improved Pact Weapon] says that you can treat a weapon as a spellcasting focus. So the thing is, could I cast a spell of that type (fireball) with my two-handed crossbow?.

Thank you in advance.

The Warcaster Feat and Arcane Focus

I’m playing a Warlock in 5e and I’m trying to make him a front line fighter/tank because we…don’t have any and our healing sucks. Thus, I’m trying everything I can to avoid being hit altogether. Mirror Image is helping, but I think some feats would really round out the character. One of these would be Medium Armor Prof. The other…Warcaster, because how can I use a shield and my Pact Weapon if it stops me from casting spells, right? So, here’s my question…

If I take Warcaster, that allows me to perform the somatic components with my hands full of weapon and shield. Does it also allow me to benefit from my Arcane Focus? Even though I can’t touch it because I have my hands full? If not, how can I cast spells at all that have material components? You have to pull the component out of your pouch to use the spell if it has a material component. If my hands are full I can’t use EITHER my focus OR my pouch!

Seeing as I’m doing this in Adventures League, I want a really clear answer. I know I have to talk it over with my DM and see if they agree, but I need a good argument. What I’m saying is, I can’t accept a house rule for this cuz it’s sanctioned. I’m really hoping there’s some kind of clarification out there for this. Rules As Intended, either focus or pouch should work if I have that feat, but Rules As Written, there is no provision, so technically, this feat is only useful for a person with their focus in one hand and a shield or weapon in the other…which makes the feat pointless. (at least this part of it)

Thanks.

Does using an arcane focus reduce the cost of adding a spell to your spellbook?

The material explanation in chapter 10 of the Players Handbook states that:

‘A character can use a component pouch or a spellcasting focus in place of the components specified for a spell. But if a cost is indicated for a component, a character must have that specified component before he or she can cast the spell.

However in the Wizard class section it says that:

‘When you find a wizard scroll of 1st level or higher you can add it to your spellbook if it is of a spell level you can prepare and if you can spare the time to decipher and copy it. Copying that spell involves reproducing the basic form of the spell, then deciphering the unique system of notation used by the wizard who wrote it….etc,etc. For each level of the spell the process takes 2 hours and costs 50 gp. The cost represents the material components you expend as you experiment with the spell to master it, as well as the fine inks you need to record it.’

However immediately after that it states that copying a spell from your own book costs only 10 gp, which I assume constitutes the cost of the fine inks, therefore if you don’t have to expend the material components via using an arcane focus, does copying another wizards spells into your own spellbook still cost 50 gp per level, or just 10 gp per level for the fine inks.

If so would this also apply for a materials pouch?

Lingering Composition: Does a Performance critical failure cost the Focus point?

TL;DR: The bard player is arguing that lingering composition is a Performance check, and another player is stating it’s Casting a Spell (Focus spell).

I have a player playing a polymath bard with lingering composition.

This player insists that when casting the composition Focus spell, on the composition’s Performance check, a critical failure is the same as a failure, and the bard doesn’t expend the Focus point (because the Focus spell requires a Performance check to determine duration, and lingering composition doesn’t have a critical failure entry, only a failure entry).

My ruling as GM is that the bard is casting a Focus spell, and that the Casting a Spell rule is the active component, not the Performance check.

Lingering Composition: https://2e.aonprd.com/Spells.aspx?ID=389

Casting a Focus Spell: https://2e.aonprd.com/Rules.aspx?ID=276

Can a bard use a musical instrument as a spellcasting focus if they aren’t proficient with it?

The bard’s spellcasting class features (PHB, pg. 53) includes the following:

Spellcasting Focus

You can use a musical instrument (found in chapter 5) as a spellcasting focus for your bard spells.

In chapter 5, it says this about musical instruments (PHB, pg. 154):

Musical Instrument. Several of the most common types of musical instruments are shown on the table as examples. If you have proficiency with a given musical instrument, you can add your proficiency bonus to any ability checks you make to play music with the instrument. A bard can use a musical instrument as a spellcasting focus. Each type of musical instrument requires a separate proficiency.

Typically, a bard will have at least one musical instrument proficiency (3 from start, 4 if they get another via background, or as few as 1 if they multiclass into bard from something else).

However, at the end of the chapter 5 quote, it says “Each type of musical instrument requires a separate proficiency”, meaning that a bard could lose their musical instrument but find or buy one that they aren’t proficient in.

The chapter 5 quote also says “If you have proficiency with a given musical instrument, you can add your proficiency bonus to any ability checks you make to play music with the instrument”, but that’s about playing it, not necessarily using it for spellcasting (and there doesn’t at time of writing seem to be a definitive answer on whether you need to play it to cast spells with it; that’s not the purpose of my question, anyway).

Finally, the chapter 5 quote also says “A bard can use a musical instrument as a spellcasting focus”, but it says it in a separate sentence to the one about proficiency, so the two sentences don’t necessarily relate to one another.

If a bard only has a musical instrument that they aren’t specifically proficient in, can they still use it to cast spells?

What is Jester using as a focus for Scrying in Critical Role?

Reading through the PHB, I found the spell Scrying, which has the following Components:

Components: V, S, M, (a focus worth at least 1000 gp, such as a crystal ball, a silver mirror or a font filled with holy water).

However, I never heard mention of such a focus in the show, even with Jester often Scrying in the wild. What object is she using?