Is there an English equivalent to the Indian proverb-"If you have the ability, even grass can be your weapon"?

Although this is not a direct paring with your proverb, it is indirectly opposed to it and in regular use.

We English tend towards self denial and as such do not easily pose prose of such positive reinforcement; Being more familiar it would seem, with self denial - "So very British!" proclaim the French. We do however say the following quite readily:- Necessity is the mother of invention.

Which I believe denotes the same.

And in response to your question ...

The skilled workman is oppressed; such that he can not bare arms, not even a blade of grass, So historically it would seem; He would take to the seas; A reflection of the fact that Britain is a small island nation.

As an edition to my initial response; I can not help but wonder if your Indian phrase is reference to the use of bamboo grass as a pen. If this is so then the phrase:- The pen is mightier than the sword, is a direct reflection of your stated proverb.

I also wonder could this be referring to a bamboo arrow?

A skilled workman can make anything out of thin air.

Not really a proverb but...

A skilled workman can MacGyver anything.

Make or repair (an object) in an improvised or inventive way, making use of whatever items are at hand:

He MacGyvered a makeshift jack with a log.

He has a shock of short red hair and a pair of rectangular-framed glasses MacGyvered with duct tape

If you have the ability and talent, you can achieve success with whatever (minimal) resources available at your disposal.

If we are permitted to replace ability and talent with resourcefulness, there's also this idiom, which means to make the most of what one has:

When life gives you lemons, make lemonade. - attributed to Elbert Hubbard by wikipedia

Just as the grass in your quote isn't normally particularly valuable as a weapon, lemons in this context refer to what would normally be considered liabilities. The resourceful person doesn't just tolerate or discard the lemons, (s)he turns them into assets, a parallel for the weapons of your quote.

I think the English equivalent would be:

You can’t keep a good man down.

The idea is that no matter what the circumstances, a “good man” will still succeed.

Very common expression, at least in U.S. English.

Nothing is impossible to a willing heart:

Someone who is eager, keen and determined can achieve anything.

[English Club]