what other support gems that increase physical damage?

what other support gems that increase physical damage? other than the 'melee physical damage' support gem

Depends very much on what skill you're using. Added Fire Damage and Physical to Lightning will work on anything. Physical Projectile Attack Damage. Melee Damage on Full Life. Multistrike/Spell Echo/Faster Attacks/Faster Casting. Increased Critical Damage. Concentrated Effect.

frost blades, but i wanted to boost its physical damage more than its elemental.
ive been using this skill since my early levels and am happy with the projectile buff but these days im seeing more monsters with elemental/cold resist and even reflect

besides physical has poison, since im a dagger shadow

I think Frost Blades is still a little difficult to scale. Straight % damage is of course best, but the next best would be % attack damage, and then % physical damage (as you mentioned).

Unfortunately, there aren't really many support gems that simply give "% increased physical damage". Your best bet is to pick up as many physical damage nodes from the passive tree as you can, as well as any attack speed that you can. I can't comment on the single target vs AoE effectiveness, but mathematically the best thing you can do is link Multistrike, Faster Attacks, and Culling Strike (off the top of my head - I could be wrong).

Anything with a "melee" tag will only affect the first strike, and not the projectiles. Likewise, anything with a "projectile" tag will not after the first strike.

I personally find it best to scale elemental and/or flat damage. And crit chance/damage if you are going crit.

Check the Frost Blades wiki page for more info on passive nodes. Edit: actually, it doesn't give much info. Best to scale damage with a weapon.

Edit: forgot about % attack damage.

Frost Blades seems like a poor skill to try to go physical-focused on, as the Melee Physical Damage support gem doesn't even apply to the projectiles the skill shoots out.

I suppose you could do a link something like:
Frost Blades
Faster Attacks
Multistrike
Fortify
Melee Physical because I can't think of anything else
???


If you really want to go Frost Blades, you're better off going elemental-focused. Something like:
Frost Blades
Physical to Lightning
Weapon Elemental Damage
Added Fire Damage
Faster Attacks
Multistrike

And then overcome resistances by using Elemental Weakness. You can now apply it as an aura-curse with Blasphemy, seems like a perfect use-case for the new skill.