Does exposing algorithm, key size and IV weaken the security? I am using an encryption program to encrypt my documents. Previously I have used PGP and AxCrypt, so I just wanted to see how this new tool encrypts the file.

This tool is keeping parameters like cipher name, key size,initialization vector etc. in plain text.

I want to know whether exposing these details can anyway help an attacker to focus his attacks.

Below are the top few lines of a sample encrypted file:

  »     ÌšÚ&gt;Öùq¸ë®ûÑÅ#Ÿ £¦É² $Náøj_{
                "artifact":"header",
                "cipher":{
                         "algorithm":"AES",
                         "IvBytes":"c6+TSc609YSMQSeorKSwAg==",
                         "mac":{
                               "enabled":false
                               },
                         "mode":"CBC",
                         "padding":"PKCS7",
                         "keySize":256,
                         "blockSize":4096,
                         "iv":"c6+TSc609YSMQSeorKSwAg=="
                         },
                "metadata":{
                            "name":{
                                    "encrypted":false,
                                    "value":"~$$tmpFDC6.tmp.bc"
                                   }
                           },
                "version":1,
                "encryptedFileKeys":[{
                                      "type":"data",
                                      "id":"2705583903525488672",
                                      "value":"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"
                                     }]
                }
No cryptography worth its salt should become less secure because its inner workings are known. It is usually assumed that the adversary has all that information when doing security proofs (Kerchoff's principle/Shannon's maxim). 

In your particular case the tool is using pretty standard crypto (AES-CBC-256) so you don't need to worry about exposing its details.

As some of the other comments point out, the tool you're using seems to have disabled the MAC (message authentication code), which opens it up to attacks in which the attacker could modify the ciphertext of a given file in deterministic ways such that you would decrypt a message of his/her choosing. I would recommend you enable it.

Another thing to note about file encryption is that the ciphertext (or the AAD -Additional Authenticated Data- if you were using authenticated encryption such as GCM) should contain the filename as well. Otherwise an attacker can swap the ciphertext of a file for another one you also encrypted.

Now, you specifically ask if this helps an attacker focus his attacks. I guess the answer is yes, if there were attacks against a particular ciphersuite, knowing that it is the one being used will facilitate the attackers task. On the other hand, if the attacker can interact with the system he/she will most likely figure it out given enough time. Or they could just throw all known attacks at it. In summary, there is nothing to gain by hiding this type of information.