About Improved Soul Covenants. I have it there for the odd time I use Covenant of Vengeance rather than Covenant of Pestilence in this build, on stuff I am not supposed to take agro on. Quick change of Covenant and stance, and I go from a 18% hate tali tank monster with 40% physical health tap, to a 7% frenzy dps. Shadow Hex is not to be underestimated. It's a big component of damage, and the whole point of having talisman equipped - getting access to that spell.
Yes you will do more damage with Covenant of Arms but Covenant of Pestilence is really good now unfeated. +5% damage to Covenant of Arms is a drop in the ocean compared to having 5 points in Shadowed Blade that will roughly double your damage from Shadow Hex.
It's a tight squeeze on points unless one could do without some of the points from General. Nick two from Sustained Rage if you'd like Dooming Presence and Air of Death. Move that point from Soul Covenants to Sacrificial Fury if you want. That comes down to what I typed under the builds;
By all means, not saying these are definitive answers but most talisman builds have likeness to these unless for certain purposes.