For the Romans facing halbadiers would be like facing armoured falxmen.
Like noble falxmen in XGM?

Actually, dismounted knights often used Halbards themselves, this precluded the use of thrown weapons but in general knights were known to employvery varried fighting styles, making use of everything from twin shortswords...
Remind me about these vanilla ninjas (Arcanii)

early knights carried shields and later knights had armour which might well have been pilum proof
Pilum stuck to their shields, making it useless, and at least the pilum will hamper the enemy's movement, and disorganize their formations, which the romans are expert to exploit...

They are still pilum cushions...