ToME: the Tales of Maj'Eyal

Doing something stupider than my normal, a yeek rogue that I intend to go anti magic with, but I don't know pretty much anything about mind stars.

Daggers let me use parry (technique/duelist 2 weapon mastery), which I've seen get to around 60% for a smallish amount of damage, but a parry will stop a crit, which I found to be very useful.

Mind stars can't be used with that skill to parry.

I've also had daggers with projection so they hit non-targets with crappy damage, but it applies on hit debuffs like 30% global speed slow on hit, x% disease on hit, anything on hit really when combined with weapons of projection let you spam out debuffs to a crowd (poison is a on hit that does spread like crazy with projection...)

So, what benefit can I get from mind stars that would be worth it over something like that with daggers?

Parry works more or less like armor in that the amount of damage it blocks is earlier than a lot of things in calculation, so it's a lot bigger than it looks at a glance, and parrying crits is a big deal, not worth skipping out on.
There's not really any big bonuses to using mindstars after Rogue got reworked, other than maybe having high stamina from leveling wil which they can deal with using other talents and getting a good chunk of base APR which usually isn't that big of a deal, they have the downside that they're usually nature or mind element, which you probably don't want.
If you really like the Mindstar Mastery tree you can go for it, it has some neat talents, but overall it's better to just use 2x daggers or 1h + dagger.

Thank you. Pumping nature would be good (the rogue poison tree is nature damage) but then undead are immune to poison, so probably not a good idea to go primarily nature damage. Will stick with daggers.

If Dual-Wielding and using a Mindstar in the Offhand, it is better to do it with classes that don't necessarily specialize in off-hand weaponry. Wyrmics and Cursed come to mind here.