Electrum wallets have Segwit address enabled wallet for low transaction fees.
Segwit is not only for lower transaction fees.
It fixed transaction malleability and enabled HTLC's (was necessary for implementations like the LN).
It is the fast and safe wallets with high securities.
Thats not true.
Hardware and paper wallets are way safer than desktop wallets itself.
Wether electrum is safer than other desktop wallets can also not be said for sure.
It using private keys for transactions
Every transaction has to be signed with private key.
This is not a feature tied to electrum...
It have an additional version such as bech32 address.
bech32 is not an 'additional version'. It is like a 'default' segwit, or 'native' segwit.
Nested P2SH (segwit addresses starting with 3.. ) are made for transition from legacy to segwit and for full backwards compatibility.
The wallet suits for only desktop not for Android phone.
There is a mobile version of electrum.
While i think there are better mobile wallets, it is still a considerable option to choose from.