I found the rather interesting, if corner case, use for this.
With Healing Strike, you can swing Healing as an effect. With Poison Strike, you can now swing a X Poison Healing attack that will heal a target that you hit, because the rule explicitly prohibits a Weapon qualifier attacks from healing, not attacks delivered by a weapon (this is confirmed by the way spell strikes of healing spells work, which is by swinging X Spell Healing with a weapon).
Making it a little more interesting, if you were to activate a Slay for that strike, you could potentially swing something like 100 Poison Healing.
Now, this combination requires 2 rituals (Poison Strike and Healing Strike), one critical attack / back attack, and one slay / assassinate, so it clearly is resource intensive. Also, short of a 40th level Orc fighter (possibly with multiple Hearty purchases), it will be hard to find a PC that can actually benefit from that much healing. But, if you have the right fighter or rogue build and the right beneficial NPC, it is potentially possible to provide a 200+ heal in a single strike.
-MS