So i recently acquired a few swords from someone who no longer fights. It looks like a few were stored improperly leaving a few thumb sized permanent dents into the foam. Question is, what can i do to fix these so i can use them as lender swords for practice. One of the swords i can feel part of the core, the other 2 dents on swords are not as severe. Thank you in advance for answering and or putting in any input.

Reblade them all they will fail at any event

Depending on methods of construction, it is possible to repair the shallower dents by excising the ruined foam and replacing it so long it is only on the striking surface (if the flat is affected it should be re-bladed). If it is anywhere near the tip this should only be done if the outermost layer is the only one affected. The more severe damage could possibly be repaired similarly so long as it isn't near the tip of the sword. Shallow dent repairs that only require a single layer of foam to be replaced can and will pass national weapon checks, deeper ones most likely will not-though if they are only to be used as loaners it really doesn't matter. If you can repair it and it passes hit-test, I would say go for it so long as the repairs don't take more time an effort than just re-blading it.

The one that you can feel core through is basically done. Re-blade as they said. If the other two are only dents as you put it and are made out of sword fries, something that Ive found to work is to leave them in my back seat on a hotter day. Had a small dent in my sword and figured it was done for so I just left it in my car. Came back to take it out 3 days later and the dent wasnt there. Idk if it was just some weird happen stance but its worth a shot before tearing them down. Mind you it doesnt work on blue foam.

Jester the heat is bad for the glue that holds the foam to the core thus that is a bad idea 90% of the people post reblade them Cuz its the best way.to solve the issue and it saves a lot of trouble and frustration those stupid tricks rarely work

Yes, but IF it does work and it is a simple fix. Its better than spending the time to cut a small piece out of the blade and expect it to hold more than a few practices. It doesnt hurt to try something thats free and doesnt require anything more than leaving something somewhere. If its bad for the glue and what not and ruins the blade... hes just gonna have to reblade it, which is exactly what hed have to do anyways. So why not take the minute chance that itd buff out the small dent and force the foam to reform. Also, Ive never had a problem with leaving a weapon in a hot car. The glue shouldnt reset nor should it unsettle. If it does then you are using far too much. Granted, dont take it out of a 110 degree car and swing it at someone, but thats more due to the foam being heated than it is to the glue getting hot enough to cause damage. They all say reblade it because its the known way to do things. Its ok to try something if it does no harm....

Set DAP does release fumes when it is heated, and skinned foam (or plastidipped shields like mine) can trap the fumes and cause separation of layers due to the pressures. It's a real thing.