https://wccftech.com/heres-why-the-hidden-blade-in-assassins-creed-valhalla-isnt-actually-hidden/

The Hidden Blade is a trademark weapon of the Assassin's Creed franchise, having appeared in all of the games released so far. Valhalla, the upcoming title due for release later this year, won't be an exception; in fact, the hidden blade was already briefly featured in the cinematics announcement trailer, as you can see from the snapshot above. However, during that trailer, the game's protagonist Eivor goes on to use it to kill his foe in a less than stealthy way, which is a departure from the hidden blade fans are familiar with.

Darby McDevitt, narrative director for Assassin's Creed Valhalla, explained why on Twitter.