I tested war caller devoted/skald with single handed sun and moon - clear out scored 30 crits, but got only one phrase. There must be some kind of restriction, so you can't get more than one at a time. I think monk with swift flurry/HBD will work simillar (but didn't tested this). In this case you want to get as much atkspd, as possible, to make it work. in this case the best options would be:
For weapons:
sun and moon - two chances for crit with one blow, 10 more acc to fire roll with ring of focused flames (single handed for better acc and hit-to-crit)
ranning's wrath - 9 more acc, +10% aspd (single handed for better acc and hit-to-crit)
WotEP - aoe damage (even if only one phrase can be aquired from one blow, you hit more targets, so more hit rolls=better chance to crit), retaliation on being missed that can do crits and generate phrase
For classes:
fighter - hit-to-crit bonuse from disciplined strikes, clear out is guaranted phrase with enough enemies and weapon modal can debuf several targets at once, more sturdy character, godd acc with conqueror stance
ranger - chanter buffs makes animal companion more tanky, best acc
monk - SF/HBD synergize with crits giving solid dps (and maybe more phrases?)
rogue, streetfighter - great aspd, so with enough acc/hit-to-crit you get fastest phrases generation and good weapon dps, but also most fragile character