Thrown weapons are not a core element of SCA youth combat, but they do have some novelty/amusement value.
Here in the East, there are basically two styles: javelins made from 3/4″ PEX with a thrusting-tip point and either fins or a pommel on the other end, or else hammers/axes made of all foam.
The rules say that weapons with a core (javelins) may not be gleaned and re-thrown, while those that are all foam may be scooped up and tossed back, which means that javelins are mostly of use in the initial few moments as the lines close, rather than being a factor throughout the engagement.
The target areas are the same as for regular weapon strikes, and at least here in the East the rule is that any direct contact in those areas constitutes a hit — no calling “light” — although I don’t think that applies if it hits a shield first, or bounces off a hand during an attempted mid-air catch.
You can make a nice throwing hammer with a single pool noodle, cut into four lengths for the head and one for the handle. Cut a triangular notch half-way through the side of each of the head pieces and arrange them around the handle, then fasten the handle securely to the head pieces and wrap everything with tape. Can be made smaller or larger as desired. Result looks imposing and is sturdy enough to survive repeated use, but light enough that kids won’t get hurt.
Here’s one I made last year. A bit beat up, but still serviceable. I put “striking edge” markings on the ends because it is sometimes used in hand-to-hand combat, but it’s really not sturdy enough to stand up to intensive use as a primary weapon — too floppy without a core.
Fighters can use a core-less foam weapon like this hammer as a regular single-handed weapon, just like a short sword etc.
(In that form it’s also allowed in single combat, although it can only be thrown in melees.)
Regular, non-thrown, weapons are supposed to have a contrasting stripe along their “edge” or “point” to indicate the areas where they do damage, as opposed to the “flat” of a sword, so that’s why I put the extra tape on those spots.
But if a fighter really used this as their primary weapon it might break or tear (or just get soft and floppy) faster than a regular weapon because it doesn’t have a solid core inside the handle.
So, it can be used as a regular weapon for a little bit before it is thrown, but that’s not its primary use.