Shield-Trained trait and being non-proficient

[kadance]

How does a Kineticist use a shield if they take the aforementioned trait?

Kineticist Proficiencies:

Weapon and Armor Proficiency: Kineticists are proficient with all simple weapons and light armor, but not shields.

Shield-trained:

You were trained to use shields as weapons. Heavy and light shields are considered simple weapons rather than martial weapons for you. Heavy shields are considered light weapons for you.

I'm getting hung up on the "simple weapons" in both entries.

My gut says they can use heavy and light shields as weapons, but not to get a shield bonus to AC.

Since they want to keep both hands free anyways, this isn't an issue for a character so much as a curiosity for me.

[Kazaan]

When it talks about shield proficiency in Weapon and Armor Proficiency blocks, it's talking about being proficient with them as armor, not as weapons. Using a shield as a weapon usually falls under Martial proficiency so any character with proficiency in all martial weapons can proficiently use a shield to attack. If you aren't proficient with shields as armor, then you take the ACP to your attack rolls as well as to Str and Dex checks. For example:

A heavy shield has a -2 ACP. If you aren't proficient with shields, you take a -2 penalty to any melee attacks you make while wearing the shield. If you are proficient with all martial weapons, you can make shield bash attacks normally (though, the -2 penalty still applies to the attack roll). If you are not proficient with martial weapons, you take -4 non-proficiency penalty to a shield bash (total -6, -4 non-prof and -2 ACP for using non-proficient armor).

Kineticist doesn't have armor proficiency for shields. But they are proficient with all simple weapons. Shield-Trained makes shield bashing count as a simple weapon, so you wouldn't take the -4 non-prof penalty, but you'd still take the -2 ACP on attack rolls unless you get armor proficiency for shields by some other means.

[kadance]

That is an excellent response. Thank you.

[Arachnofiend]

Shield-Trained is primarily useful to classes that get proficiency in shields but not martial proficiency (IE Clerics and Bards).