One of my players wants to play a Black Templars marine, so I came up with the following chapter traits:
Righteous Zeal: Black Templars receive +Rank bonus dice when making a melee attack as part of a charge.
Intolerance (Tradition): Black Templars are intolerant of psykers and mutants. They suffer a +2DN penalty for Interaction tests or combined actions involving a mutant or psyker.
The benefit is slightly stronger (bonus dice vs rerolls) but less generally usable (only on charge vs all melee attacks) than the Blood Angels benefit. It also ties thematically into the 40k tabletop rules, where the chapter gains a bonus on charges.
The drawback is based on a fusion of the Dark Angels and Raven Guard chapter drawbacks (so worse when it applies), but will be applicable less often (only to psykers and mutants rather than anyone outside the chapter).
1) Bonus dice on the charge to hit in melee is very different from Blood Angels (re-roll up to rank damage dice
in melee), partially because it is harder, in general, to acquire damage dice to be re-rolled, than to acquire accuracy dice to be re-rolled. A better comparison would be to another chapter that re-rolls or adds dice to a skill (since we're discussing bonus Weapon Skill dice): Raven Guard re-roll Stealth and have Hide In Plain Sight, Space Wolves add to Awareness (the best skill in any RPG). Dark Angels get full-on Unnatural Ballistic Skill, but only during a Held Action. I conclude your benefit is relatively balanced. However, most of the traits seem based on the current tabletop traits, so I would ask you to consider changing it to: Black Templars add their Rank to Athletics and Pilot tests made to Charge or Ram, respectively, and increase the attack bonus from Charging to Rank. This is a slightly weaker bonus to hit (at R1 you are no more accurate than anyone else on the charge) in exchange for more versatility (you are better at things like including a Jump into a Charge).
2) The penalty needs to apply when the Templar believes the target is a mutant or psyker - e.g. it should be possible to Deceive them into being mistaken, particularly if they lack the tools to check. What exactly is a mutant here - is it anyone the Templar thinks has a mutation? Mental disorder? Corruption? Abhumans? Mutant is not a keyword, but Psyker is, so this segues into my opinion that you need special rules for handling BT Psykers - current fluff suggests that the Templars never
actually field Psykers, even by accident, but it's unknown whether this is a gene-seed issue (e.g. it might kill any latent psyker it's put into) or something else (you have room to decide your universe's BTs do something exotic, like have every member regularly checked by the Black Ships and get kicked out if they register as a psyker, or even let the BTs have a relic that can check for them).