Well, katana & broadsword simply have a special attack power that grants a temporary defense buff, so all you need do is use that power sometime in your attack chain to gain the benefit. Similarly, radiation melee has a toggle that you activate to provide the effect, and you use the heal power as needed. Savage melee is the only one I mentioned that has an actual mechanic to it; Some attacks build up stacks of blood frenzy, which is what gives you the recharge and end cost reduction buffs, while others consume those stacks to gain some additional benefit. Frankly, though, I tend to *not* consume the stacks, as I prefer the aforementioned buffs, (the powers that consume blood frenzy gain a highlighted circle around them when you can gain their effects, so it's pretty easy to notice).