This is because a weapon’s Base ATK is one of the most valuable sources of ATK for ATK-scaling characters. So it’s often better to use 4-star or 5-star weapons on these characters because of their higher Base ATK. Still, it works well on a few units in-game – and it can even compete with some 4-star polearms. The White Tassel is a 3-star polearm with a Base ATK of 401 and 23.4% CRIT rate secondary stat at Level 90. And at Refinement Rank 5 (R5), its passive increases the wielder’s normal attack damage by 48%. Characters that can best use White Tassel are DPS units that don’t mainly scale from ATK and can use CRIT stats – most notably, Hu Tao and Cyno. These two units do benefit from ATK, but not as much as units like Xiao or Rosaria. Instead, Hu Tao mainly scales from HP, while Cyno mainly benefits from Elemental Mastery. So they can freely benefit from White Tassel’s CRIT rate stat despite its low Base ATK. Plus they often perform normal attacks, so they also greatly benefit from White Tassel’s strong passive. Similarly, any future polearm user can also use White Tassel as long as they’re a DPS unit that can CRIT, don’t scale entirely from ATK, and often performs normal attacks. Additionally, here’s a cheat sheet of White Tassel’s synergy with all current playable characters in early-game and late-game.
Great means that White Tassel is one of the character’s best 3-star to 4-star weapons. Good means that White Tassel works on the character, but it’s outperformed by other polearms – namely, 4-star craftable, free, or gacha weapons. Not recommended means that the character has significantly better and equally accessible options – or they simply don’t benefit from White Tassel’s stats/passive.