Being you're a skinner, you know you can remove DF's wave with one of the effect_nt's floating around I'm sure. (also Rufus's return to skinning when?). And yeah it's kind of a "rude" weapon, this is why I'm thankful this is in the works. it'll save a lotta heartache with the average player who is trying to learn to use it but is spited by FO's and others with resta, who have a history of anger with the weapon. Rightly so with how they've been treated.
I'm not so sure about a shield, but it does need something to counterbalnace. DF is really good so a drawback (formerly the resta chance) should be a thing. Unit management+the cost/hunt to create the unit could definitely be the drawbacks. With a shield, The ATA pentalty of not having a Red ring would only truly hurt the lesser classes like HUnl and Humr more than it'd nerf Hucl with her high ata, and the broken HUct who both have FT's to negate evade anyway. So that's why I think that's probably a bad idea.
I mean its true one could say, that the low health is already a drawback but the good players aren't gonna get hit anyway. Either way I think planning around a unit slot loss is more than adequate, as on the spot unit management requires planning and thought, which is more than a limiting factor against the inexperienced. And TA players wont even be using the unit as they already play around resta/flow use.