In reply to leon 1:
From here:
https://www.eurostar.com/uk-en/travel-info/travel-planning/luggage/sports-a...
If you’re travelling with any of these items, you’ll need to contact Eurodespatch, our registered luggage service: ice axes and other climbing and mountaineering equipment, javelins, spears and spear guns, crossbows, crossbow bolts, longbows, longbow arrows and starting pistols, swords or starting pistols. Keep in mind that these are all subject to approval and security checks.