OK. So played around with this a bit and worked out a few things. Firstly, last shot power applies the 15% damage to the shot itself, similar to hunter/open wounds (tested with rep pistol, applies to a full burst shot if you have 8 or less ammo remaining).
I see a potentially interesting synergy with rep pistol, which historically has run hunter, and generally relied on prize bounty, and not shooting too much between blessed shots being up to sustain ammo. Potentially now you could run hunter, last shot power, melee kill reload, and either weapon swap buff or cruel fortune.
Weapon swap buff is not ideal for getting melee power with rep pistol, since its alt shot seems to only give you 1 stack of melee damage, even if you hit multiple enemies with it Conversely though rep pistol’s alt fire only consumes 1 stack of bonus range damage generated from melee attacking, and this can be used to offset the loss of Open Wounds, especially when firing your last clip, since you’ll then also be geting the 15% from last shot power (+30% on that shot in theory).
Or you can run cruel fortune so you don’t have to wait 10 seconds for your rep pistol to briefly not feel like a water pistol (which frankly it does without a crit).
In either case, if you empy your last alt shot into an elite, assuming it dies you get a clip and a half back (12 shots) immediately, as well as the juicy last shot power buff for 15 seconds (which will also apply to any of those 12 shots you decide to fire within 15 seconds). If instead you need to empty your last shots into a special or something else, well next elite you kill you’re getting ammo, so you won’t be empty for long.
Stacking all this together leads to some pretty insane bursts of melee damage. Hunter + Last shot power is giving you 35% power + 15% attack speed for 10 seconds, with last shot lingering another 5 after hunter fades. If you’re running weapon swap buff and emptied your last clip spamming left click instead of alt fire, you’re now at 50% power +15% attack speed for the first 6 atack. Stonks. The absolute carnage you could cause to a patrol emptying your last clip then running in with a 1h axe is pretty nutty.
Now I haven’t playtested all this properly yet, and I know a lot of this is finicky to do in practice, but I definitely think what we have now is infinitely more interesting and useful than necessary means on live. Pretty sure Volley bow could also run the build outlined very effectively.