When they changed the way the leaches work, they made the heavier, slower weapons have higher amounts, to compensate for how little the weapons were actually leaching under the new system.
The original Quell, Pacify, and the other one (Calm?) had like 60% or so Mana Leach. At the time, this was a very, very good amount, and these weapons were highly sought-after and duped.
Under the new system, however, that kind of sucks. So these items' mana leaches were "translated" to 100%.
If yours didn't have it straight out, it was probably one of those labeling bugs we have in this game periodically, that corrects itself at server-up.
Unlike the originals of these items, the Replicas seem to be aimed mostly at people who want to use, rather than collect, the items. Thus, this is one of those cases where the properly-labeled item is actually more valuable than the improperly-labeled one.
-Galen's player