If you want crits to feed your phrase count you should consider Sun & Moon. Also legendary, but it has two separate attack rolls, both can crit. Skald's mechanic only allows 1 phrase generation per "strike" max, so you won't ever get 2 phrases even if two crit happen during one swing, but the chance to get a phrase in the first place with two attack rolls is significantly(!) higher than with only one attack roll.
It's also better with Confounding Blind (which generates more crits).
Second weapon can be whatever, Squid's Grasp, Katana Taga, Rust's Poignard has an additional attack roll that doesn't proc on every attack but only occasionally - but that additional roll also raises the chance to get a phrase a bit. Another good weapon is Rännig's Wrath - it's not legendary but comes with +4 extra accuracy and is faster. Faster attacks = more crits in a given timeframe.