Neat, that's handy that you can get dark gifts without having to sacrifice a gift. As I said in the first preview for dark gifts, they simply didn't keep up with normal feats because of the opportunity cost, but now I can imagine several of them being viable in heroics. Since you would get access at level 8 (I assume you can't access the feature earlier, but if you can bank a Offerings to the Dark Powers on another life/character and pass it over to access it immediately that would be neat too) you can wait until you're past the very low levels when some of these drawbacks are prohibitive, and with the upgrades in legendary that seems like a good way to make it feel better.
I do think the upgrade for Touch of Death is a bit underwhelming- deathblock is pretty common, and for example the Pale Master tree's capstone is (supposed to- wiki says it's bugged but wiki could be out of date) a source of deathblock that is correlated with a negative healing source, Dark Apostate is a cleric and therefore can get it, and of course items are a common source of deathblock and by legendary it's very easy to get them. I don't have any particular suggestion here, but my gut instinct is that it feels worse than the others, which cut back penalties in a significant way, make the penalties also have a beneficial mechanic, or buff the primary ability, while this one just feels like it's grabbed becauuse it's vaguely thematic.
I already think Touch of Death is maybe the weakest (in terms of being an interesting ability, not necessarily usefulness if you heal from negative energy since the drawback can basically be moot) of the dark gifts, so giving them something you probably already have in your gear feels pretty mediocre, since it would be a good opportunity to give them some flavor.
