I’ve been thinking about this one for awhile. You can get onslaught stacks from the vast majority of default attack replacers and fleshwarped strikes from Theodin’s weapon feels a bit left out in the cold. 2-3 onslaught stacks would probably not break anything and it would make the weapon a bit more competitive in the 1.3.1 FoA era.
I’ve been thinking about this too in combination with the aether shadow strike conduit being the worst of the bunch (no CDR, no charges), but obviously you can play Theodin’s weapon in a number of ways and you don’t need to play DW melee nightblade with shadow strike.