When in doubt, check with the person responsible for weapon checks at your LARP, but training weapons like this are considered NOT safe for most non-historical LARPs.
Always check with your Herald/Reeve/Rules Guy before bringing a new weapon onto the field. They'll be happy to help. Usually, they'll be checking for a few things. I'll break these up by categories, since the answer varies a bit by what you're doing:
Historical LARPs like SCA generally have very strict safety standards, but since everyone is wearing armor they break down to require that weapons be dulled and metal. There may be restrictions on chain length for hinged weapons as well. Again, this varies from organization to organization and even chapter to chapter.
Fantasy Combat LARPs with No Player Contact like Amtgard or Hiraeth will generally be much more towards the pool noodle end of things. There is a minimum diameter for weapons and no minimum weight. This helps keep everyone safe, and cores out of people's eyes. Speaking of, these kinds of larps don't allow metal weapons of any stripe, so without knowing the core material (the rigid shaft in the center of most foam weapons) it will probably be tossed.
Fantasy Combat LARPs with Player Contact like Dagohir allow for minimum weights and diameters for their weapons, but allow contact between players. These sorts of Larps will also find metal cores unacceptable. In general due ot the player contact, Contact larps like this require cloth covers on non-shield equipment, since that prevents jagged edges that can occur sometimes on plastic-coated weapons.
Sci-Fi/Apocalypse NERF LARPs are actually the most welcoming of this kind of weapon, but it will varies. The new-ish Fall of Man LARP would allow this weapon since it is similar to the hand-held weapons that NERF produces. This is probably the only one outside a Historical LARP that would allow this on the field, but you'd need to be very careful with it.
The Martial Melee Weapons Table lists all the weapons with Reach.
These weapons are:
- Glaive
- Halberd
- Lance
- Pike
- Whip
This table can be found here in the Basic Rules or listed in this DNDBeyond search.
The Reach property has never been added or removed from any weapon, as evidenced by this most recent printing of the Player's Handbook Errata.
Best Answer
The systems I have played tend to have a fairly standard set of rules for weapons- as you might expect given that there are a limited number of traders and they need to be able to sell to players across different systems for their work to be viable.
The largest system I've played ( The Lorien Trust, about 5000 players at large events, weapon check guidelines here ) uses the following standard:
The system I have been playing most recently ( Profound Decisions, Empire, around 1000 player events, weapon guidelines here ) has a similar standard but they do allow stabbing spears ( at least 6" of soft foam at the tip ) which can be used one handed but must only be used for stabbing.
The important thing in both systems is that all weapons must be checked by specialist staff before they are used and that no weapons that have not passed check should be in the game area. A weapons checker has the right to judge a weapon unsafe in their view even if it conforms theoretically to the guidelines. There is usually some visual indicator of check ( UV stamps or coloured bands are examples I have seen used often ) and weapons checkers have the right to check any weapon at any time and typically you have another round of weapons check on the way into a battlefield. This is particularly important because even well made weapons will break with use and one that passes on Friday may have been stood on or damaged by Sunday morning, rendering it unsafe.
Also having refs on the field during combat to ensure that fights are safe and fun for everyone is essential. Anyone using a weapon that is clearly unsafe or using a safe weapon in an unsafe way needs to be pulled up and the weapon/player removed from the field as necessary.