The -5 to hit +10 to damage is just straight-up a bad choice for a rogue in almost all cases. Two attacks is something rogues can already get with dual-wielding or crossbow mastery. Rerolling 1s and 2s is very strong. If you’re worried about that, maybe require the weapon to be light or to not be two-handed or versatile.So no one has gone with Halberd, Pollarm Master, Great Weapon Master, with a dip into fighter for great weapon fighting? You now have two attacks -5 to hit +10 to damage and you reroll 1s and 2s for the sneak attack dice. Variant Human allows this at 5th level.