i'm at a low enough level that i really don't have to worry about dying with my whm. the whole time i was partying, would use benediction without hesitation when needed. I LOVED pulling the hate onto me and dying for the party. best thing about it is that once the beast turns around, hes faced with 5 full hp fighters, who are all very, very pissed that the monster killed thier friend.
Well, that certainly is one uniquely optimistic view of using benediction.
Personally, I feel there's only two acceptable reasons for a whm to use Benediction.
The first being low-less low level whms (1-40 roughly), if things start to go bad towards the end of a fight; ei. things start to go bad, the mob has low hp, but so does about half the party. Benediction is okay here, because if the whm uses it, there is a pretty good chance they'll still come out alive, IF THEY STAND STILL then the rest of the party is free to whail on the mob and quite possibly kill it before the whm dies.
**What I see most often is, mob has half health still, party is starting to get beat up, whm low on mp - Benediction! NO.. because then the whm dies, and unless everyone already started running everyone else will drop. Or once the whm uses benediction, he starts running around like he/she is on fire. Hello? We cant fight the mob if its moving, and then the whm dies, pissed because we didnt kill it. WTF.** (will refer back to this at bottom)
Second acceptable reason, is once you get into higher level parties. Tanks have more abilities at thier disposal for removing hate, theres the trusty Thf SaTa, multiple provokes from anyone who has it, as well as all the hate grabbing techniques jobs have. As a Drk/War I even help out by provoking, then using souleater, last resort, and nuking if need be.
Thing is at the higher levels, Its possible to get rid of the hate that benediction gets, at lower levels, benediction's an end battle last resort.
Nobody wants their whm to get killed, at any level. A good tank can keep this from happening 100% of the time. Until Benedition is used (at low levels).
When I was starting out as a War and War/Mnk, I tell you, I was the best damn tanking warrior you ever saw ^^ *blush* Key is to have distance between the melee and the mages. A good party knows this. That distance is there so if the tank loses hate he/she has a few seconds to hit that provoke macro and regain control of the hate. In that few seconds the mob is running over to whatever mage got the hate, but the distance allows it not to be able to reach the mage before provoke is used. Basically the mob would at most only get halfway between the melee and mages, and turn around to fight the tank again. It's a relatively simple strategy, and it saves mages from even having to get touched, assuming they have a good quick tank, and the blms dont nuke.
**In the situation noted with ** the best thing to do in a failing party is for the tank to sacrifice him/herself for the sake of the team, not the whm. What I would do as tank is tell everyone to disengage and zone immediately "or you will die" as they are running away I give it my all, I havent played pally yet, but if i was one id use my 2hr and start running the oppisite direction from my teamates as well as be using what ever defense buffs i might have. As a warrior I use whatever defense buffs I have and continue fighting the mob while walking backwards away from the direction my teamates went. **
This gives them all a larger gap from the mob, when I die, they live and escape to saftey. As a tank I certainly dont mind taking one for the team, its pretty much your job. And your teamates will appreciate the tank taking one for the team a lot more than the whm being killed. Generally speaking the whm's like it better that way too. ^^

Oye this is a long post. heh