Lacerator is great to use on swich in PvM, when you need to deal with PI. I did it all the time with my wolf and I like it more then atma scarab or reapers toll.
As soon as you cast amp, swich back to main weapon.
Well, I used a Lacerator for a while on my WW-barb until I had my Grief, but since the grief was a very low roll I actually did more max damage with the low noneth lacerator, After some time I got bored of the barb and sold the grief, I had him hold my Eth Lacerator while leveling my thrower and found him to deal rather good dmg compared to the grief, this probably because I had very low %edmg from gear and such causing the different statbonus for throwing weapons (0,75*Str+0,75*Dex) instead of (1,0*Str) to be main damage factor (I had max block thus alot of dex)
So Lacerators can deal decent dmg, but they won't beat most runewords if rest of eq is fine (for example if I had equipped fortitude the grief would've been MUCH greater dmg)
The amplify dmg and OW is what can save it then. If you're duels last long enough to leave room for switching for amp and back without the duel being over by then it can be worth a shot, but I won't promise any results...
amp damage on a low damage weapon is still crappy damage. Duel any real smiter, fireclaw, or fury druid... any real duel lasts only a few hits (unless you have godly 8-10k life?). You don't just get to hit the smiter a few times so u get the amp... then the "tides change" and you win? Either go for the one-two hit kill or lose. If you wanna be sneaky and amp them, I suggest use gavel of pain on switch, then switch back to your ebotd/SS and pwn them. Life tap is different, with pally's etc, because that WILL save your arsss in mid duel but relying on amp won't do jack. It swings slow, doesn't offer any range benefit, and... the name doesn't sound cool either..."lacerator", yuck. It has sorta a feminine ring to it... I mean, Grief...Breath of the Dying... u hear that and you're like, "dam, I better stay away". "Lacerator", they're like... i can take this girl. sry, but neways...
I suggest... use gavel of pain to amp them. If you really wanna be cheap if you're dueling another fury or smiter, I'd try using bone prison and a range 5 weapon. right before they get to you prison them and outrange them to catch them off guard in their charge. Trust me, I've done and its frustrating 4 them ^^ even when I'd lose it'd ergh them every time when i'd keep stalling them, hit them, then run and stall them again