emm...people do include doylak sigit in farming builds , but its not needed in all + is of an attribute not always needed in some farming spots, it lowers your movement by 75% , not your attack spee , each point of strength is 1% armor pentration which does raise your damage slighty.
Dolyak lowers your movement speed, attack is unaffected. It's armour bonus and duration both go up with the more str you have.
I used to use it in my war/mo hydra farming build...but these days I rather put points into Tactics, and I see the 1% armour penetration per 1 str attrib as a bit feeble unless my team needs a certain build.
I only ever use Doylak Sygnet in UW if Im the only warrior or in Sorrows if Im using the gear build, then you are taking all the damage and movement isnt necessary.
Dolyak really is not used onless soloing. I use it in all of my solo axe builds but never when im with a group. It can be used however and can be an affective spell. It does not affect your attack speed;p
Tanking is MUCH easier with dolyak sig. I use a w/n with dolyak sig, enfeebling blood, shield stance, defensive stance, and anything else is filler. Also, the nolani fire wand. Cant have those Aatxes riposting you!