Unfortunately, yes. Pact of the Blade makes you proficient with the weapon, but doesn't negate the Heavy property, so you'd still need a 13 in Strength to wield it without disadvantage on attack rolls.
Edit: Completely missed the '2014' bit. My bad. Same answer applies, but the penalty is different.
When I conjure Great Sword as pact of blade in D&D 2014 Version
does it need strength atleast 13 to wield it or not?
No, it doesn't. The Strength requirement for using Heavy weapons is only present in the 2024 rules. It does apply to Pact weapons if you're playing under the 2024 rules, though.
If you're playing under the 2014 rules, the Heavy property imposes a different penalty: if the wielder is Small size or smaller (like a Halfling or a Gnome, for instance) they have disadvantage on attacks with Heavy weapons. This penalty still applies if it's a Pact of the Blade weapon.
When I conjure Great Sword as pact of blade in D&D 2014 Version
does it need strength atleast 13 to wield it or not?
Unfortunately, yes. Pact of the Blade makes you proficient with the weapon, but doesn't negate the Heavy property, so you'd still need a 13 in Strength to wield it without disadvantage on attack rolls.
Edit: Completely missed the '2014' bit. My bad. Same answer applies, but the penalty is different.
No, it doesn't. The Strength requirement for using Heavy weapons is only present in the 2024 rules. It does apply to Pact weapons if you're playing under the 2024 rules, though.
If you're playing under the 2014 rules, the Heavy property imposes a different penalty: if the wielder is Small size or smaller (like a Halfling or a Gnome, for instance) they have disadvantage on attacks with Heavy weapons. This penalty still applies if it's a Pact of the Blade weapon.
pronouns: he/she/they