You might consider:

A stiff fore-arm guard which would be similar in function
to a soccer shin-guard. It would be made much stronger however.
Kevlar matte and 2-chemical polyester resin, like they use for
Canoes. Preparing the matte, you could separate the weave to
allow for small air holes.
A vacuum bag which I have only read about, could keep the resin
to a minimum, and the whole thing would be lighter, as a result.

A light fore-arm guard allows for quick response, and speed
is critical. So keep the "tools" somewhere else, like on your
belt.

A few (thin) patches of open cell foam could provide a
stand-off and padding from the arm. This may keep you from
getting a fungal rash on your arm.

For the wrist and hand, how much flexibility do you want.
It is a problem. Yeah, they sell various gloves for meat
cutters and police. I am guessing that the gloves would
stop or minimize a Slash attack, but not a Stabbing attack.

Have you had any training in open hand Martial Arts or
weapons MA or weapons sports? (rhetorical question).
Without recent workouts, your reactions may be way too slow,
even with a superb fore-arm protector.

"It would be made much stronger however."

I'm not sure about storing much in it but for forearms you don't really need it to be much tougher than a set of good quality soccer shinguard. I know this from a local bouncer who started wearing fiber-reinforced shin guards on his forearms after a fight where he tried to block a bad stool and had his arm broken.

Now he says he has a lot confidence in these simple glass reinforced nylon units. As an experiment a friend swung a baseball bat and he easily blocked it without so much as a bruise.

These units are thick translucent nylon with a glass reinforced stripe down the middle. He says he used a jigsaw to modify the shin guards to fit on his forearms. He wears them under a long-sleeve shirt. He also wears matching shinguard. When a drunken free-for-alls break out the guys typically like to swing the furniture and the ladies like to abuse the shins. He also wears lifters gloves.

I'm not sure I qualify as a person who really needs such gear. I tend to avoid crowds. But if your plans or habits put you in situations where fisticuffs or pounding through a crowd is likely I think a sturdy version of the athletic guards on shins and forearms, otherwise known as greaves and vambraces, sound like a good idea.

You might find the lighter plastic version lighter, more comfortable and plenty strong enough. You might look into the armor commonly worn by guards for prisoner extraction. Fully armored up they look like imperial storm troopers.

I've known people use the shin guards (crickets often use forearm protection for their leading arm) and wire mesh (light gauge chicken wire - wrap several layers around the forearm for slash protection).

1 thing to remember, is that a lot of places will look on anything you load up with like this as a 'weapon' - it may be defensive in intent, but carrying anything to use as a tool in an altercation runs this risk.

Hmm, I am thinking of the old leather cuff guards Duke Wayne used to wear. A good piece of soft split suede under a piece of thin laquered rawhide, with a piece of 3 oz calf or goat skin over the outside, laced up on the inside, about 4 inches wide. The lacing allows for an almost infinite custom fit. Tough, yet flexible. May not hold up to a smashing knife strike or a hard thrust, but ought to deflect the usual slash strokes. I suppose you could put some cartridge loops around the outside or some such for mounting acourterments.

You could also braid some rawhide and piano wire into a bracer of sorts, that would be much more impervious, but a bit more bulky.

I'm even thinking you could braid some 550 cord into a sort of bracer with all sorts of things wove into it.

Hmm, the more I think about it, the more I like the braiding idea...