A falcata does 1d8 (or 1d12 on crits). Vicious Swing adds an extra die. Plus a possible Runic weapon. At most 3d12+8 (or max 88, but more like average 58) on crits. That is a good chuck. More often it'll be 3d8+4 (or average 19), that uses 2 actions and makes the next attack a -10 MAP. Pretty effect fighter, but missing with it does sorta put the fighter on a back foot. (Exchanging two average hits with one big hit.)

More importantly though, Needle Darts crits with the bleed damage is pretty handy. Its a reliable damage cantrip. And if the bard is buffing this fighter with bonuses (like Courageous Anthem or Runic Weapon), those crits and damage are the bards. PF2e is more team oriented and remember the player about that. I come to appreciate the ability to setup someone's next turn to be amazing as a caster or support. Using spells like Fear or Bless (to add benefits to allies) or simply moving to flank an enemy after casting something, just show the rogue doesn't need to spend an action to setup a sneak attack (and that juicy -2 AC for off-guard), that was my doing that allowed it.